Articles that include a polymer foam and method for preparing same

ABSTRACT

Polymer foam articles prepared by melt-mixing a polymer composition and a plurality of microspheres, at least one of which is an expandable polymeric microsphere, under process conditions, including temperature and shear rate, selected to form an expandable extrudable composition; and extruding the composition through a die.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 09/714,658, filed Nov. 16, 2000, now U.S. Pat. No. 6,797,371,issued Sep. 28, 2004 which is a continuation of InternationalApplication PCT/US99/17344, having an international filing date of Jul.30, 1999, which is a continuation-in-part and which claims priority toU.S. patent application Ser. No. 09/127,774, filed Jul. 31, 1998, nowU.S. Pat. No. 6,103,152, issued Aug. 15, 2000, all of which are assignedto the assignee of the present application. The entire disclosure of theprior application is considered as being part of the disclosure of theaccompanying application and is hereby incorporated by referencetherein.

FIELD OF THE INVENTION

This invention relates to preparing articles that include a polymerfoam.

BACKGROUND OF THE INVENTION

Articles incorporating a polymer foam core are known. The foam includesa polymer matrix and is characterized by a density that is lower thanthe density of the polymer matrix itself. Density reduction is achievedin a number of ways, including through creation of gas-filled voids inthe matrix (e.g., by means of a blowing agent) or inclusion of polymericmicrospheres (e.g., expandable microspheres) or non-polymericmicrospheres (e.g., glass microspheres).

SUMMARY OF THE INVENTION

In a first aspect, the invention features an article that includes apolymer foam having a substantially smooth surface. The foam may beprovided in a variety of shapes, including a rod, a cylinder, a sheet,etc. In some embodiments, e.g., where the foam is provided in the formof a sheet, the foam has a pair of major surfaces, one or both of whichare substantially smooth. The foam includes a plurality of microspheres,at least one of which is an expandable polymeric microsphere.

As used herein, a “polymer foam” refers to an article that includes apolymer matrix in which the density of the article is less than thedensity of the polymer matrix alone.

A “substantially smooth” surface refers to a surface having an Ra valueless than about 75 micrometers, as measured by laser triangulationprofilometry according to the procedure described in the Examples,infra. Preferably, the surface has an Ra value less than about 50micrometers, more preferably less than about 25 micrometers. The surfaceis also characterized by the substantial absence of visually observablemacroscopic defects such as wrinkles, corrugations and creases. Inaddition, in the case of an adhesive surface, the surface issufficiently smooth such that it exhibits adequate contact and, thereby,adhesion to a substrate of interest. The desired threshold level ofadhesion will depend on the particular application for which the articleis being used.

An “expandable polymeric microsphere” is a microsphere that includes apolymer shell and a core material in the form of a gas, liquid, orcombination thereof, that expands upon heating. Expansion of the corematerial, in turn, causes the shell to expand, at least at the heatingtemperature. An expandable microsphere is one where the shell can beinitially expanded or further expanded without breaking. Somemicrospheres may have polymer shells that only allow the core materialto expand at or near the heating temperature.

The article may be an adhesive article or a non-adhesive article. An“adhesive article” is an article having a surface available for bondingthat is either tacky at room temperature (i.e., pressure sensitiveadhesive articles) or becomes tacky when heated (i.e., heat-activatedadhesive articles). An example of an adhesive article is a foam thatitself is an adhesive, or an article that includes one or more separateadhesive compositions bonded to the foam, e.g., in the form of acontinuous layer or discrete structures (e.g., stripes, rods, filament,etc.), in which case the foam itself need not be an adhesive. Examplesof non-adhesive articles include non-adhesive foams and adhesive foamsprovided with a non-adhesive composition, e.g., in the form of a layer,substrate, etc., on all surfaces available for bonding.

The foam preferably is substantially free of urethane crosslinks andurea crosslinks, thus eliminating the need for isocyanates in thecomposition. An example of a preferred material for the polymer foam isan acrylic polymer or copolymer. In some cases, e.g., where highcohesive strength and/or high modulus is needed, the foam may becrosslinked. The polymer foam preferably includes a plurality ofexpandable polymeric microspheres. The foam may also include one or morenon-expandable microspheres, which may be polymeric or non-polymericmicrospheres (e.g., glass microspheres).

Examples of preferred expandable polymeric microspheres include those inwhich the shell is essentially free of vinylidene chloride units.Preferred core materials are materials other than air that expand uponheating.

The foam may contain agents in addition to microspheres, the choice ofwhich is dictated by the properties needed for the intended applicationof the article. Examples of suitable agents include those selected fromthe group consisting of tackifiers, plasticizers, pigments, dyes, solidfillers, and combinations thereof. The foam may also include gas-filledvoids in the polymer matrix. Such voids typically are formed byincluding a blowing agent in the polymer matrix material and thenactivating the blowing agent, e.g., by exposing the polymer matrixmaterial to heat or radiation.

The properties of the article may be adjusted by bonding and/orco-extruding one or more polymer compositions (e.g., in the form ofcontinuous layers or discrete structures such as stripes, rods,filament, etc.) to or into the foam. Both foamed and non-foamedcompositions may be used. A composition may be bonded directly to thefoam or indirectly, e.g., through a separate adhesive.

The article may be used as a “foam-in-place” article. The termfoam-in-place refers to the ability of the article to be expanded orfurther expanded after the article has been placed at a desiredlocation. Such articles are sized and placed in a recessed area or on anopen surface, and then exposed to heat energy (e.g., infrared,ultrasound, microwave, resistive, induction, convection, etc.) toactivate, or further activate, the expandable microspheres or blowingagent. Such recessed areas can include a space between two or moresurfaces (e.g., parallel or non-parallel surfaces) such as found, forexample, between two or more opposing and spaced apart substrates, athrough hole or a cavity. Such open surfaces can include a flat oruneven surface on which it is desirable for the article to expand afterbeing applied to the surface. Upon activation, the foam expands due tothe expansion of the microspheres and/or blowing agent, therebypartially or completely filling the recess or space, or therebyincreasing the volume (e.g. height) of the article above the opensurface.

It can be desirable for the foam to comprise a substantiallyuncrosslinked or thermoplastic polymeric matrix material. It can also bedesirable for the matrix polymer of the foam to exhibit some degree ofcrosslinking. Any crosslinking should not significantly inhibit orprevent the foam from expanding to the degree desired. One potentialadvantage to such crosslinking is that the foam will likely exhibitimproved mechanical properties (e.g., increase cohesive strength)compared to the same foam with less or no crosslinking. In the case offoams having a curable polymer matrix, exposure to heat can alsoinitiate cure of the matrix.

It can further be desirable for the foam-in-place article to comprisemultiple layers, discrete structures or a combination thereof (See, forexample, FIGS. 4-6 and the below discussion thereof), with each layerand discrete structure having a difference in the way it foams-in-place(e.g., using expandable microspheres, blowing agents or a combinationthereof), a difference in the degree to which it can be expanded inplace, or a combination thereof. For example, the concentration ofexpandable microspheres and/or blowing agents can be different, the typeof expandable microspheres and/or blowing agents can be different, or acombination thereof can be used. In addition, for example, one or moreof the layers and discrete structures can be expandable in place whileone or more other layers and discrete structures can be unexpandable inplace.

In a second aspect, the invention features an article (e.g., an adhesivearticle, as defined above) comprising a polymer foam (as defined above)that includes: (a) a plurality of microspheres, at least one of which isan expandable polymeric microsphere (as defined above), and (b) apolymer matrix that is substantially free of urethane crosslinks andurea crosslinks. The matrix includes a blend of two or more polymers inwhich at least one of the polymers in the blend is a pressure sensitiveadhesive polymer (i.e., a polymer that is inherently pressure sensitive,as opposed to a polymer which must be combined with a tackifier in orderto form a pressure sensitive composition) and at least one of thepolymers is selected from the group consisting of unsaturatedthermoplastic elastomers, acrylate-insoluble saturated thermoplasticelastomers, and non-pressure sensitive adhesive thermoplastic polymers.

The foam preferably has a substantially smooth surface (as definedabove). In some embodiments, the foam has a pair of major surfaces, oneor both of which may be substantially smooth. The foam itself may be anadhesive. The article may also include one or more separate adhesivecompositions bonded to the foam, e.g., in the form of a layer. Ifdesired, the foam may be crosslinked.

The polymer foam preferably includes a plurality of expandable polymericmicrospheres. It may also include non-expandable microspheres, which maybe polymeric or non-polymeric microspheres (e.g., glass microspheres).The properties of the article may be adjusted by directly or indirectlybonding one or more foamed or non-foamed polymer compositions to thefoam.

The invention also features multi-layer articles that include theabove-described foam articles provided on a major surface of a firstsubstrate, or sandwiched between a pair of substrates. Examples ofsuitable substrates include wood substrates, synthetic polymersubstrates, and metal substrates (e.g., metal foils).

In a third aspect, the invention features a method for preparing anarticle that includes: (a) melt mixing a polymer composition and aplurality of microspheres, one or more of which is an expandablepolymeric microsphere (as defined above), under process conditions,including temperature, pressure and shear rate, selected to form anexpandable extrudable composition; (b) extruding the composition througha die to form a polymer foam (as defined above); and (c) at leastpartially expanding one or more expandable polymeric microspheres beforethe polymer composition exits the die. It can be preferable for most, ifnot all, of the expandable microspheres to be at least partiallyexpanded before the polymer composition exits the die. By causingexpansion of the expandable polymeric microspheres before thecomposition exits the die, the resulting extruded foam can be producedto within tighter tolerances, as described below in the DetailedDescription.

It is desirable for the polymer composition to be substantiallysolvent-free. That is, it is preferred that the polymer compositioncontain less than 20 wt. % solvent, more preferably, containsubstantially none to no greater than about 10 wt. % solvent and, evenmore preferably, contain no greater than about 5 wt. % solvent.

In a fourth aspect, the invention features another method for preparingan article that includes: (a) melt mixing a polymer composition and aplurality of microspheres, one or more of which is an expandablepolymeric microsphere (as defined above), under process conditions,including temperature, pressure and shear rate, selected to form anexpandable extrudable composition; and (b) extruding the compositionthrough a die to form a polymer foam (as defined above). After thepolymer foam exits the die, enough of the expandable polymericmicrospheres in the foam remain unexpanded or, at most, partiallyexpanded to enable the polymer foam to be used in a foam-in-placeapplication. That is, the extruded foam can still be further expanded toa substantial degree at some later time in the application. Preferably,the expandable microspheres in the extruded foam retain most, if notall, of their expandability.

In a fifth aspect, the invention features another method for preparingan article that includes: (a) melt mixing a polymer composition and aplurality of microspheres, one or more of which is an expandablepolymeric microsphere (as defined above), under process conditions,including temperature, pressure and shear rate, selected to form anexpandable extrudable composition; and (b) extruding the compositionthrough a die to form a polymer foam (as defined above) having asubstantially smooth surface (as defined above). It is also possible toprepare foams having a pair of major surfaces in which one or both majorsurfaces are substantially smooth.

Polymers used according to the present invention can preferably possessa weight average molecular weight of at least about 10,000 g/mol, andmore preferably at least about 50,000 g/mol. It can also be preferablefor the polymers used according to the present invention to exhibitshear viscosities measured at a temperature of 175° C. and a shear rateof 100 sec⁻¹, of at least about 30 Pascal-seconds (Pa-s), morepreferably at least about 100 Pa-s and even more preferably at leastabout 200 Pa-s.

The article may be an adhesive article (as defined above), e.g., apressure sensitive adhesive article or a heat-activated adhesivearticle. In some embodiments, the foam itself is an adhesive.

Both the expandable extrudable composition and the extruded foampreferably include a plurality of expandable polymeric microspheres (asdefined above). The extruded foam and the expandable extrudablecomposition may also include one or more non-expandable microspheres,which may be polymeric or non-polymeric microspheres (e.g., glassmicrospheres).

The expandable extrudable composition may be co-extruded with one ormore additional extrudable polymer compositions, e.g., to form a polymerlayer on a surface of the resulting foam. For example, the additionalextrudable polymer composition may be an adhesive composition. Othersuitable additional extrudable polymer compositions include additionalmicrosphere-containing compositions.

The method may also include crosslinking the foam. For example, the foammay be exposed to thermal, actinic, or ionizing radiation orcombinations thereof subsequent to extrusion to crosslink the foam.Crosslinking may also be accomplished by using chemical crosslinkingmethods based on ionic interactions.

The invention provides foam-containing articles, and a process forpreparing such articles, in which the articles can be designed toexhibit a wide range of properties depending upon the ultimateapplication for which the article is intended. For example, the foamcore may be produced alone or in combination with one or more polymercompositions, e.g., in the form of layers to form multi-layer articles.The ability to combine the foam with additional polymer compositionsoffers significant design flexibility, as a variety of different polymercompositions may be used, including adhesive compositions, additionalfoam compositions, removable compositions, layers having differentmechanical properties, etc. In addition, through careful control of thefoaming operation it is possible to produce a foam having a pattern ofregions having different densities.

Both thin and thick foams can be produced. In addition, both adhesiveand non-adhesive foams can be produced. In the latter case, the foam maybe combined with one or more separate adhesive compositions to form anadhesive article. In addition, it is possible to prepare foams from anumber of different polymer matrices, including polymer matrices thatare incompatible with foam preparation processes that rely on actinicradiation-induced polymerization of microsphere-containingphotopolymerizable compositions. Examples of such polymer matrixcompositions include unsaturated thermoplastic elastomers andacrylate-insoluble saturated thermoplastic elastomers. Similarly, it ispossible to include additives such as ultraviolet-absorbing pigments(e.g., black pigments), dyes, and tackifiers that could not be usedeffectively in actinic radiation-based foam processes. It is furtherpossible, in contrast to solvent-based and actinic radiation-based foamprocesses, to prepare foams having a substantially homogeneousdistribution of microspheres. In addition, the present expanded foam(i.e., a foam containing microspheres that have been at least partiallyexpanded) can have a uniform size distribution of the expandedmicrospheres from the surface to the center of the foam. That is, thereis no gradient of expanded microsphere sizes from the surface to thecenter of the foam, e.g., like that found in expanded foams which aremade in a press or a mold. Expanded foams that exhibit such a sizedistribution gradient of their expanded microspheres can exhibit weakermechanical properties than such foams that have a uniform sizedistribution of the expanded microspheres. Oven foaming of these foamcompositions require long residence times in the high temperature ovendue to the poor thermal conductivity of the foams. Long residence timesat high temperatures can lead to polymer and carrier (e.g., releaseliner) degradation. In addition, poor heat transfer can also lead tofoams containing non-uniform expansion, causing a density gradient. Sucha density gradient can significantly decrease the strength and otherwisedetrimentally impact the properties of the foam. The process associatedwith oven foaming is also complicated and usually requires uniqueprocess equipment to eliminate large scale corrugation and buckling ofthe planar sheet. For a reference on oven foaming see, for example,Handbook of Polymeric Foams & Foam Technology, eds: D. Klempner & K. C.Frisch, Hanser Publishers, New York, N.Y., 1991.

Foams with a substantially smooth surface can be produced in a singlestep. Accordingly, it is not necessary to bond additional layers to thefoam in order to achieve a smooth-surfaced article. Substantiallysmooth-surfaced foams are desirable for a number of reasons. Forexample, when the foam is laminated to another substrate, thesubstantially smooth surface minimizes air entrapment between the foamand the substrate. Moreover, in the case of adhesive foams thesubstantially smooth surface maximizes contact with a substrate to whichthe foam is applied, leading to good adhesion.

The extrusion process enables the preparation of multi-layer articles,or articles with discrete structures, in a single step. In addition,when foaming occurs during the extrusion, it is possible, if desired, toeliminate separate post-production foaming processes. Moreover, bymanipulating the design of the extrusion die (i.e., the shape of the dieopening), it is possible to produce foams having a variety of shapes.

In addition, the present method may include heating the article afterextrusion to cause further expansion. The additional expansion may bedue to microsphere expansion, activation of a blowing agent, or acombination thereof.

It is also possible to prepare “foam-in-place” articles by controllingthe process temperature during the initial foam preparation such thatexpansion of the microspheres is minimized or suppressed. The articlecan then be placed at a location of use or application, (e.g., in arecessed area or on an open surface) and heated, or exposed to anelevated temperature to cause microsphere expansion. “Foam-in-place”articles can also be prepared by including a blowing agent in theexpandable extrudable composition and conducting the extrusion processunder conditions insufficient to activate the blowing agent. Subsequentto foam preparation, the blowing agent can be activated to causeadditional foaming.

Other features and advantages of the invention will be apparent from thefollowing description of the preferred embodiments thereof, and from theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1( a) is a plot showing the Ra value obtained by lasertriangulation profilometry for the sample described in Example 12.

FIG. 1( b) is a photomicrograph obtained by scanning electron microscopy(SEM) of the surface of the sample described in Example 12.

FIG. 2( a) is a plot showing the Ra value obtained by lasertriangulation profilometry for the sample described in Example 58.

FIG. 2( b) is a SEM photomicrograph of the surface of the sampledescribed in Example 58.

FIG. 3 is a perspective drawing showing a foam having a patternedsurface.

FIG. 4 is a perspective drawing of an article featuring a foam combinedwith an additional polymer composition.

FIG. 5 is a perspective drawing of an article featuring a foam combinedwith two additional polymer compositions.

FIG. 6 is a perspective drawing of an article featuring a foam combinedwith multiple additional polymer compositions.

FIG. 7 is a schematic drawing of an extrusion process for preparingarticles according to the invention.

FIG. 8 is a plot showing the peel force applied in a direction (MD)parallel to the filament direction as a function of displacement forExamples 73, 77 and 78.

FIG. 9 is a plot showing the peel force applied in a direction (CD)perpendicular to the filament direction as a function of displacementfor Examples 73, 77 and 78.

FIG. 10 is a plot showing the peel force applied in a direction (MD)parallel to the filament direction as a function of displacement forExamples 72, 79, 80 and 81.

FIG. 11 is a plot showing the peel force applied in a direction (CD)perpendicular to the filament direction as a function of displacementfor Examples 72, 79, 80 and 81.

FIGS. 12 a-12 b are SEM photomicrographs of cross-sections, as viewed inthe machine direction (MD) and crossweb direction (CD), respectively, ofthe unoriented foam described in Example 86.

FIGS. 12 c-12 d are SEM photomicrographs of cross-sections, as viewed inthe machine direction (MD) and crossweb direction (CD), respectively, ofthe axially oriented foam described in Example 86.

FIGS. 13 a and 13 b are SEM photomicrographs of cross-sections, asviewed in the machine direction (MD) and crossweb direction (CD),respectively, of the polymer blend foam described in Example 23.

DETAILED DESCRIPTION

Article

The invention features articles that include a polymer foam featuring apolymer matrix and one or more expandable polymer microspheres.Examination of the foam by electron microscopy reveals that the foammicrostructure is characterized by a plurality of enlarged polymericmicrospheres (relative to their original size) distributed throughoutthe polymer matrix. At least one of the microspheres (and preferablymore) is still expandable, i.e., upon application of heat it will expandfurther without breaking. This can be demonstrated by exposing the foamto a heat treatment and comparing the size of the microspheres obtain byelectron microscopy to their pre-heat treated size (also obtained byelectron microscopy).

The foam is further characterized by a surface that is substantiallysmooth, as defined in the Summary of the Invention, above. Lasertriangulation profilometry results and scanning electronphotomicrographs are shown in FIGS. 1 and 2 for representative acrylicfoams having substantially smooth surfaces prepared as described inExamples 12 and 58, respectively, described in further detail below.Each of the photomicrographs of FIGS. 1( b) and 2(b) includes a 100micrometer long measurement bar B. Each of the samples in FIGS. 1( b)and 2(b) have been sectioned, with the surface portion being light andthe sectioned portion being dark.

The foam may be provided in a variety of forms, including a sheet, rod,or cylinder. In addition, the surface of the foam may be patterned. Anexample of such a foam is shown in FIG. 3. Foam 100 is in the form of asheet having a uniform pattern of bumps 102 arranged on the surface ofthe foam. Such articles are prepared by differential foaming, asdescribed in more detail, below. The differential foaming processcreates bumps 102 having a density different from the density of thesurrounding areas 104.

A variety of different polymer resins, as well as blends thereof, may beused for the polymer matrix as long as the resins are suitable for meltextrusion processing. For example, it may be desirable to blend two ormore acrylate polymers having different compositions. A wide range offoam physical properties can be obtained by manipulation of the blendcomponent type and concentration. The particular resin is selected basedupon the desired properties of the final foam-containing article. Themorphology of the immiscible polymer blend that comprises the foammatrix can enhance the performance of the resulting foam article. Theblend morphology can be, for example, spherical, ellipsoidal, fibrillar,co-continuous or combinations thereof. These morphologies can lead to aunique set of properties that are not obtainable by a single componentfoam system. Such unique properties may include, for example,anisotropic mechanical properties, enhanced cohesive strength. Themorphology (shape & size) of the immiscible polymer blend can becontrolled by the free energy considerations of the polymer system,relative viscosities of the components, and most notably the processing& coating characteristics. By proper control of these variables, themorphology of the foam can be manipulated to provide superior propertiesfor the intended article.

FIGS. 13 a and 13 b show SEM photomicrographs of the microstructure ofthe immiscible polymer blend of Example 23 (i.e., 80 wt % of the HotMelt Composition 1 and 20 wt % of Kraton™ D1107). The Kraton™ D1107 wasstained with OsO₄ so as to appear white, which enables this phase to beviewed. These Figures demonstrate that the Kraton™ D1107 phase is acomplex morphology consisting of fibrillar microstructures, with sizesof approximately 1 μm. In FIG. 13 a, the Kraton™ D1107 fibrillar phasesare shown in cross-section and appear spherical.

One class of useful polymers includes acrylate and methacrylate adhesivepolymers and copolymers. Such polymers can be formed by polymerizing oneor more monomeric acrylic or methacrylic esters of non-tertiary alkylalcohols, with the alkyl groups having form 1 to 20 carbon atoms (e.g.,from 3 to 18 carbon atoms). Suitable acrylate monomers include methylacrylate, ethyl acrylate, n-butyl acrylate, lauryl acrylate,2-ethylhexyl acrylate, cyclohexyl acrylate, iso-octyl acrylate,octadecyl acrylate, nonyl acrylate, decyl acrylate, and dodecylacrylate. The corresponding methacrylates are useful as well. Alsouseful are aromatic acrylates and methacrylates, e.g., benzyl acrylateand cyclobenzyl acrylate.

Optionally, one or more monoethylenically unsaturated co-monomers may bepolymerized with the acrylate or methacrylate monomers; the particularamount of co-monomer is selected based upon the desired properties ofthe polymer. One group of useful co-monomers includes those having ahomopolymer glass transition temperature greater than the glasstransition temperature of the acrylate homopolymer. Examples of suitableco-monomers falling within this group include acrylic acid, acrylamide,methacrylamide, substituted acrylamides such as N,N-dimethyl acrylamide,itaconic acid, methacrylic acid, acrylonitrile, methacrylonitrile, vinylacetate, N-vinyl pyrrolidone, isobornyl acrylate, cyano ethyl acrylate,N-vinylcaprolactam, maleic anhydride, hydroxyalkylacrylates,N,N-dimethyl aminoethyl (meth)acrylate, N,N-diethylacrylamide,beta-carboxyethyl acrylate, vinyl esters of neodecanoic, neononanoic,neopentanoic, 2-ethylhexanoic, or propionic acids (e.g., available fromUnion Carbide Corp. of Danbury, Conn. under the designation “Vynates”,vinylidene chloride, styrene, vinyl toluene, and alkyl vinyl ethers.

A second group of monoethylenically unsaturated co-monomers which may bepolymerized with the acrylate or methacrylate monomers includes thosehaving a homopolymer glass transition temperature less than the glasstransition temperature of the acrylate homopolymer. Examples of suitableco-monomers falling within this class include ethyloxyethoxy ethylacrylate (Tg=−71° C.) and a methoxypolyethylene glycol 400 acrylate(Tg=−65° C.; available from Shin Nakamura Chemical Co., Ltd. under thedesignation “NK Ester AM-90G”).

A second class of polymers useful for the polymer matrix of the foamincludes acrylate-insoluble polymers. Examples include semicrystallinepolymer resins such as polyolefins and polyolefin copolymers (e.g.,based upon monomers having between 2 and 8 carbon atoms such as lowdensity polyethylene, high density polyethylene, polypropylene,ethylene-propylene copolymers, etc.), polyesters and co-polyesters,polyamides and co-polyamides, fluorinated homopolymers and copolymers,polyalkylene oxides (e.g., polyethylene oxide and polypropylene oxide),polyvinyl alcohol, ionomers (e.g., ethylene-methacrylic acid copolymersneutralized with base), and cellulose acetate. Other examples ofacrylate-insoluble polymers include amorphous polymers having asolubility parameter (as measured according to the Fedors' technique)less than 8 or greater than 11 such as polyacrylonitrile, polyvinylchloride, thermoplastic polyurethanes, aromatic epoxies, polycarbonate,amorphous polyesters, amorphous polyamides, ABS copolymers,polyphenylene oxide alloys, ionomers (e.g., ethylene-methacrylic acidcopolymers neutralized with salt), fluorinated elastomers, andpolydimethyl siloxane.

A third class of polymers useful for the polymer matrix of the foamincludes elastomers containing ultraviolet radiation-activatable groups.Examples include polybutadiene, polyisoprene, polychloroprene, randomand block copolymers of styrene and dienes (e.g., SBR), andethylene-propylene-diene monomer rubber.

A fourth class of polymers useful for the polymer matrix of the foamincludes pressure sensitive and hot melt adhesives prepared fromnon-photopolymerizable monomers. Such polymers can be adhesive polymers(i.e., polymers that are inherently adhesive), or polymers that are notinherently adhesive but are capable of forming adhesive compositionswhen compounded with tackifiers. Specific examples includepoly-alpha-olefins (e.g., polyoctene, polyhexene, and atacticpolypropylene), block copolymer-based adhesives (e.g., di-block,tri-block, star-block and combinations thereof), natural and syntheticrubbers, silicone adhesives, ethylene-vinyl acetate, andepoxy-containing structural adhesive blends (e.g., epoxy-acrylate andepoxy-polyester blends).

The expandable microspheres feature a flexible, thermoplastic, polymericshell and a core that includes a liquid and/or gas which expands uponheating. Preferably, the core material is an organic substance that hasa lower boiling point than the softening temperature of the polymericshell. Examples of suitable core materials include propane, butane,pentane, isobutane, neopentane, and combinations thereof.

The choice of thermoplastic resin for the polymeric shell influences themechanical properties of the foam. Accordingly, the properties of thefoam may be adjusted through appropriate choice of microsphere, or byusing mixtures of different types of microspheres. For example,acrylonitrile-containing resins are useful where high tensile andcohesive strength are desired, particularly where the acrylonitrilecontent is at least 50% by weight of the resin, more preferably at least60% by weight, and even more preferably at least 70% by weight. Ingeneral, both tensile and cohesive strength increase with increasingacrylonitrile content. In some cases, it is possible to prepare foamshaving higher tensile and cohesive strength than the polymer matrixalone, even though the foam has a lower density than the matrix. Thisprovides the capability of preparing high strength, low densityarticles.

Examples of suitable thermoplastic resins which may be used as the shellinclude acrylic and methacrylic acid esters such as polyacrylate;acrylate-acrylonitrile copolymer; and methacrylate-acrylic acidcopolymer. Vinylidene chloride-containing polymers such as vinylidenechloride-methacrylate copolymer, vinylidene chloride-acrylonitrilecopolymer, acrylonitrile-vinylidene chloride-methacrylonitrile-methylacrylate copolymer, and acrylonitrile-vinylidenechloride-methacrylonitrile-methyl methacrylate copolymer may also beused, but are not preferred where high strength is desired. In general,where high strength is desired, the microsphere shell preferably has nomore than 20% by weight vinylidene chloride, more preferably no morethan 15% by weight vinylidene chloride. Even more preferred for highstrength applications are microspheres having essentially no vinylidenechloride units.

Examples of suitable commercially available expandable polymericmicrospheres include those available from Pierce Stevens (Buffalo, N.Y.)under the designations “F30D,” “F80SD,” and “F100D.” Also suitable areexpandable polymeric microspheres available from Akzo-Nobel under thedesignations “Expancel 551,” “Expancel 461,” and “Expancel 091.” Each ofthese microspheres features an acrylonitrile-containing shell. Inaddition, the F80SD, F100D, and Expancel 091 microspheres haveessentially no vinylidene chloride units in the shell.

The amount of expandable microspheres is selected based upon the desiredproperties of the foam product. In general, the higher the microsphereconcentration, the lower the density of the foam. In general, the amountof microspheres ranges from about 0.1 parts by weight to about 50 partsby weight (based upon 100 parts of polymer resin), more preferably fromabout 0.5 parts by weight to about 20 parts by weight.

The foam may also include a number of other additives. Examples ofsuitable additives include tackifiers (e.g., rosin esters, terpenes,phenols, and aliphatic, aromatic, or mixtures of aliphatic and aromaticsynthetic hydrocarbon resins), plasticizers, pigments, dyes,non-expandable polymeric or glass microspheres, reinforcing agents,hydrophobic or hydrophilic silica, calcium carbonate, toughening agents,fire retardants, antioxidants, finely ground polymeric particles such aspolyester, nylon, or polypropylene, stabilizers, and combinationsthereof. Chemical blowing agents may be added as well. The agents areadded in amounts sufficient to obtain the desired end properties.

The properties of the article may be adjusted by combining one or morepolymer compositions with the foam. These additional compositions maytake several forms, including layers, stripes, etc. Both foamed andnon-foamed compositions may be used. A composition may be bondeddirectly to the foam or indirectly, e.g., through a separate adhesive.In some embodiments, the additional polymer composition is removablybonded to the foam; such compositions can subsequently be stripped fromthe foam.

Examples of articles featuring combinations of a foam and one or moreadditional polymer compositions are shown in FIGS. 4-6. Referring toFIG. 4, there is shown an article 200 featuring a plurality of foamstripes 202 arranged in a patterned and combined within a separatepolymer layer 204. The density of stripes 202 is different from thedensity of polymer layer 204 surrounding the stripes.

FIG. 5 depicts another article 300 in which a plurality of foam stripes302 are arranged in a pattern and combined within a separate polymerlayer 304. Layer 304, in turn, is bonded to yet another polymer layer306 on its opposite face. The density of stripes 302 is different fromthe density of layer 304 surrounding the stripes.

FIG. 6 depicts yet another article 400 in which a plurality of foamstripes 402 are embedded within a multilayer structure featuring polymerlayers 404, 406, and 408. The density of stripes 402 is different fromthe density of layers 404, 406, and 408.

Preferably, additional polymer compositions are bonded to the foam coreby co-extruding the extrudable microsphere-containing composition withone or more extrudable polymer compositions, as described in greaterdetail, below. The number and type of polymer compositions are selectedbased upon the desired properties of the final foam-containing article.For example, in the case of non-adhesive foam cores, it may be desirableto combine the core with one or more adhesive polymer compositions toform an adhesive article. Other examples of polymer compositionsprepared by co-extrusion include relatively high modulus polymercompositions for stiffening the article (semi-crystalline polymers suchas polyamides and polyesters), relatively low modulus polymercompositions for increasing the flexibility of the article (e.g.,plasticized polyvinyl chloride), and additional foam compositions.

Extrusion Process

Referring to FIG. 7, there is shown an extrusion process for preparingan article that includes a polymer foam featuring a polymer matrix andone or more expandable polymer microspheres. According to the process,polymer resin is initially fed into a first extruder 10 (typically asingle screw extruder) which softens and grinds the resin into smallparticles suitable for extrusion. The polymer resin will eventually formthe polymer matrix of the foam. The polymer resin may be added toextruder 10 in any convenient form, including pellets, billets,packages, strands, and ropes.

Next, the resin particles and all additives except the expandablemicrospheres are fed to a second extruder 12 (e.g., a single or twinscrew extruder) at a point immediately prior to the kneading section ofthe extruder. Once combined, the resin particles and additives are fedto the kneading zone of extruder 12 where they are mixed well. Themixing conditions (e.g., screw speed, screw length, and temperature) areselected to achieve optimum mixing. Preferably, mixing is carried out ata temperature insufficient to cause microsphere expansion. It is alsopossible to use temperatures in excess of the microsphere expansiontemperature, in which case the temperature is decreased following mixingand prior to adding the microspheres.

Where no mixing is needed, e.g., where there are no additives, thekneading step may be omitted. In addition, where the polymer resin isalready in a form suitable for extrusion, the first extrusion step maybe omitted and the resin added directly to extruder 12.

Once the resin particles and additives have been adequately mixed,expandable polymeric microspheres are added to the resulting mixture andmelt-mixed to form an expandable extrudable composition. The purpose ofthe melt-mixing step is to prepare an expandable extrudable compositionin which the expandable polymeric microspheres and other additives, tothe extent present, are distributed substantially homogeneouslythroughout the molten polymer resin. Typically, the melt-mixingoperation uses one kneading block to obtain adequate mixing, althoughsimple conveying elements may be used as well. The temperature,pressure, shear rate, and mixing time employed during melt-mixing areselected to prepare this expandable extrudable composition withoutcausing the microspheres to expand or break; once broken, themicrospheres are unable to expand to create a foam. Specifictemperatures, pressures, shear rates, and mixing times are selectedbased upon the particular composition being processed.

Following melt-mixing, the expandable extrudable composition is meteredinto extrusion die 14 (e.g., a contact or drop die) through a length oftransfer tubing 18 using a gear pump 16 that acts as a valve to controldie pressure and thereby prevent premature expansion of themicrospheres. The temperature within die 14 is preferably maintained atsubstantially the same temperature as the temperature within transfertubing 18, and selected such that it is at or above the temperaturerequired to cause expansion of the expandable microspheres. However,even though the temperature within tubing 18 is sufficiently high tocause microsphere expansion, the relatively high pressure within thetransfer tubing prevents them from expanding. Once the compositionenters die 14, however, the pressure drops. The pressure drop, coupledwith heat transfer from the die, causes the microspheres to expand andthe composition to foam within the die. The pressure within the diecontinues to drop further as the composition approaches the exit,further contributing to microsphere expansion within the die. The flowrate of polymer through the extruder and the die exit opening aremaintained such that as the polymer composition is processed through thedie, the pressure in the die cavity remains sufficiently low to allowexpansion of the expandable microspheres before the polymer compositionreaches the exit opening of the die.

The shape of the foam is dictated by the shape of the exit opening ofthe die 14. Although a variety of shapes may be produced, the foam istypically produced in the form of a continuous or discontinuous sheet.The extrusion die may be a drop die, contact die, profile die, annulardie, or a casting die, for example, as described in Extrusion Dies:Design & Engineering Computation, Walter Michaelis, Hanser Publishers,New York, N.Y., 1984, which is incorporated herein by reference in itsentirety.

It can be preferable for most, if not all, of the expandablemicrospheres to be partially or mostly expanded before the polymercomposition exits the die. By causing expansion of the expandablepolymeric microspheres before the composition exits the die, theresulting extruded foam can be produced to within tighter density andthickness (caliper) tolerances. A tighter tolerance is defined as themachine (or longitudinal) direction and crossweb (or transverse)direction standard deviation of density or thickness over the averagedensity or thickness (σ/x), respectively. The σ/x that is obtainableaccording to the present invention can be less than about 0.2, less thanabout 0.1, less than about 0.05, and even less than about 0.025. Withoutany intention to be so limited, the tighter tolerances obtainableaccording to the present invention is evidenced by the followingexamples.

As shown in FIG. 7, the foam may optionally be combined with a liner 20dispensed from a feed roll 22. Suitable materials for liner 20 includesilicone release liners, polyester films (e.g., polyethyleneterephthalate films), and polyolefin films (e.g., polyethylene films).The liner and the foam are then laminated together between a pair of niprollers 24. Following lamination or after being extruded but beforelamination, the foam is optionally exposed to radiation from an electronbeam source 26 to crosslink the foam; other sources of radiation (e.g.,ion beam, thermal and ultraviolet radiation) may be used as well.Crosslinking improves the cohesive strength of the foam. Followingexposure, the laminate is rolled up onto a take-up roll 28.

If desired, the smoothness of one or both of the foam surfaces can beincreased by using a nip roll to press the foam against a chill rollafter the foam exits die 14. It is also possible to emboss a pattern onone or both surfaces of the foam by contacting the foam with a patternedroll after it exits die 14, using conventional microreplicationtechniques, such as, for example, those disclosed in U.S. Pat. No.5,897,930 (Calhoun et al.), U.S. Pat. No. 5,650,215 (Mazurek et al.) andthe PCT Patent Publication No. WO 98/29516A (Calhoun et al.), all ofwhich are incorporated herein by reference. The replication pattern canbe chosen from a wide range of geometrical shapes and sizes, dependingon the desired use of the foam. The substantially smooth surface of theextruded foam enables microreplication of the foam surface to a higherdegree of precision and accuracy. Such high quality microreplication ofthe present foam surface is also facilitated by the ability of the foamto resist being crushed by the pressure exerted on the foam during themicroreplication process. Microreplication techniques can be usedwithout significantly crushing the foam because the foam includesexpandable microspheres that do not collapse under the pressure of themicroreplication roll, compared to foaming agents like gas.

The extrusion process may be used to prepare “foam-in-place” articles.Such articles find application, for example, as gaskets or othergap-sealing articles, vibration damping articles, tape backings,retroreflective sheet backings, anti-fatigue mats, abrasive articlebackings, raised pavement marker adhesive pads, etc. Foam-in-placearticles may be prepared by carefully controlling the pressure andtemperature within die 14 and transfer tubing 18 such that micro sphereexpansion does not occur to any appreciable extent. The resultingarticle is then placed in a desired area, e.g., a recessed area or opensurface and heated at, or exposed to, a temperature sufficiently high tocause microsphere expansion.

Foam-in-place articles can also be prepared by incorporating a chemicalblowing agent such as 4,4′-oxybis(benzenesulfonylhydrazide) in theexpandable extrudable composition. The blowing agent can be activatedsubsequent to extrusion to cause further expansion, thereby allowing thearticle to fill the area in which it is placed.

The extrusion process can also be used to prepare patterned foams havingareas of different densities. For example, downstream of the point atwhich the article exits the die, the article can be selectively heated,e.g., using a patterned roll or infrared mask, to cause microsphereexpansion in designated areas of the article.

The foam may also be combined with one or more additional polymercompositions, e.g., in the form of layers, stripes, rods, etc.,preferably by co-extruding additional extrudable polymer compositionswith the microsphere-containing extrudable compositions. FIG. 7illustrates one preferred co-extrusion process for producing an articlefeaturing a foam sandwiched between a pair of polymer layers. As shownin FIG. 7, polymer resin is optionally added to a first extruder 30(e.g., a single screw extruder) where it is softened and melt mixed. Themelt mixed resin is then fed to a second extruder 32 (e.g., a single ortwin screw extruder) where they are mixed with any desired additives.The resulting extrudable composition is then metered to the appropriatechambers of die 14 through transfer tubing 34 using a gear pump 36. Theresulting article is a three-layer article featuring a foam core havinga polymer layer on each of its major faces.

It is also possible to conduct the co-extrusion process such that atwo-layer article is produced, or such that articles having more thanthree layers (e.g., 10-100 layers or more) are produced, by equippingdie 14 with an appropriate feed block, or by using a multi-vaned ormulti-manifold die. Tie layers, primers layers or barrier layers alsocan be included to enhance the interlayer adhesion or reduce diffusionthrough the construction.

In addition, we also can improve the interlayer adhesion of aconstruction having multiple layers (e.g., A/B) of differentcompositions by blending a fraction of the A material into the B layer(A/AB). Depending on the degree of interlayer adhesion will dictate theconcentration of A in the B layer. Multilayer foam articles can also beprepared by laminating additional polymer layers to the foam core, or toany of the co-extruded polymer layers after the article exits die 14.Other techniques which can be used include coating the extruded foam(i.e., extrudate) with stripes or other discrete structures.

Post processing techniques, which may include lamination, embossing,extrusion coating, solvent coating, or orientation, may be performed onthe foam to impart superior properties. The foams may be uni-axially ormulti-axially oriented (i.e., stretched in one or more directions) toproduce foam structures that contain microvoids between or a separationof the foam matrix and the expandable microspheres (See Examples 85-92).FIGS. 12 a-12 d show SEM micrographs of the microstructure of the foamof Example 86, before (FIGS. 12 a and 12 b) and after (FIG. 12 c and 12d) uniaxial orientation. FIGS. 12 a and 12 c are cross-sectional viewsof the foam microstructure as seen in the machine direction (MD). Thatis, for FIGS. 12 a and 12 c, the foam was sectioned perpendicular to thedirection the foam flows as it exits the die and viewed in the directionof flow. FIGS. 12 b and 12 d are cross-sectional views of the foammicrostructure as seen in the crossweb direction (CD). That is, forFIGS. 12 b and 12 d, the foam was sectioned parallel to the directionthe foam flows as it exits the die and viewed in the directionperpendicular to the direction of flow.

The selection of the foam matrix, expandable microspheretype/concentration and orientation conditions can affect the ability toproduce microvoided foam materials. Orientation conditions include thetemperature, direction(s) of stretch, rate of stretch, and degree ofstretch (i.e., orientation ratio). It is believed that the interfacialadhesion between the foam matrix and the expandable microspheres shouldbe such to allow at least some debonding to occur around themicrospheres upon stretching (i.e., orientation). It is also believedthat poor interfacial adhesion can be preferable. Furthermore, it has befound desirable for the foam matrix to be capable of undergoingrelatively high elongation (e.g., at least 100%). Orientation of thefoam samples can cause a reduction in density of the foam (e.g., up toabout 50%) due to the formation of microvoids between the foam matrixand the microspheres that form during orientation. Microvoids can remainafter the stretching (orientation) process or they can disappear (i.e.,collapse but the interface remains unbonded). In addition, delaminationbetween the foam matrix and the microspheres, with or without anoticeable density reduction, can result in a significant alteration ofthe mechanical properties of the foam (e.g., increase in flexibility,reduction in stiffness, an increase in softness of foam, etc.).Depending on the ultimate foam application, the material selection andthe orientation conditions can be selected to generate desiredproperties.

It can be desirable for the extrudable polymer composition to becrosslinkable. Crosslinking can improve the cohesive strength of theresulting foam. It may be desirable for the crosslinking of theextrudable polymer to at least start between the melt mixing step andexiting of the polymer through the die opening, before, during or afterfoaming, such as by the use of thermal energy (i.e., heat activatedcuring). Alternatively or additionally, the extrudable polymercomposition can be crosslinked upon exiting the die such as, forexample, by exposure to thermal, actinic, or ionizing radiation orcombinations thereof. Crosslinking may also be accomplished by usingchemical crosslinking methods based on ionic interactions. The degree ofcrosslinking can be controlled in order to influence the properties ofthe finished foam article. If the extruded polymer is laminated, asdescribed herein, the polymer extrudate can be crosslinked before orafter lamination. Suitable thermal crosslinking agents for the foam caninclude epoxies and amines. Preferably, the concentrations aresufficiently low to avoid excessive crosslinking or gel formation beforethe composition exits the die.

Use

The foam-containing articles are useful in a variety of applicationsincluding, for example and not by way of limitation, aerospace,automotive, and medical applications. The properties of the articles aretailored to meet the demands of the desired applications. Specificexamples of applications include vibration damping articles, medicaldressings, tape backings, retroreflective sheet backings, anti-fatiguemats, abrasive article backings, raised pavement marker adhesive pads,gaskets, and sealants.

The invention will now be described further by way of the followingexamples.

EXAMPLES

Test Methods

Surface Roughness

The surface topology as a function of displacement was measured using aLaser Triangulation Profilometer (Cyberscan 200, available fromCyberoptics of Minneapolis, Minn.). All the measurements were collectedat room temperatures using a HeNe laser (654 nm) with a point rangeselector resolution of 1 micrometer (PRS-40). The laser was programmedto move across the sample in discrete jumps of 25 micrometers with atotal of 50 jumps (total length=1250 micrometers). The sample sizemeasured 1250×1250 micrometers. The roughness data was leveled bysubtracting a linear regression fit of the data and positioning theaverage at zero. The surface roughness, Ra, was calculated using thefollowing relationship:

$\begin{matrix}{R_{a} = {\frac{1}{L_{m}}{\int_{0}^{Lm}{{{z(x)}}\ {\mathbb{d}x}}}}} & (1)\end{matrix}$where R_(a) is the surface roughness, L_(m) is the total displacementlength, and z is the height at a displacement of x.90° Peel Adhesion

A foam pressure-sensitive adhesive sheet is laminated to a sheet of0.127 mm thick anodized aluminum. A strip of tape measuring 1.27 cm by11.4 cm is cut from the sheet and applied to a metal substrate that waspainted with a basecoat/clear coat automotive paint composition (RK-7072from DuPont Co.) The strip is then rolled down using four total passesof using a 6.8 kg metal roller. The sample is aged at one of thefollowing conditions before testing:

-   -   1 hour at room temperature (22° C.)    -   3 days at room temperature (22° C.)    -   7 days at 70° C.    -   5 days at 100° C. and 100% humidity After aging, the panel is        mounted in an Instron™ Tensile Tester so that the tape is pulled        off at a 90 degree angle at a speed of 30.5 cm per minute.        Results are determined in pounds per 0.5 inch, and converted to        Newtons per decimeter (N/dm).        T-Peel Adhesion

This test is performed according to ASTM D3330-87 except as specified. Astrip of foam tape measuring 11.43 cm by 1.27 cm wide is laminatedbetween two anodized aluminum strips (10.16 cm long by 1.59 cm wide by0.127 mm thick). The laminated test sample is conditioned for at least 1hour at room temperature (22° C.), and then tested for cohesive strengthusing an Instron™ Tensile tester at a 180° peel and a crosshead speed of30.48 inches per minute. The test results are recorded in pounds per ½inch width and results are converted to newtons/decimeter (N/dm).

Tensile and Elongation

This test is performed according to ASTM D412-92 except as specified. Asample of the foam is cut into a “dog bone” shape having a width of0.635 mm in the middle portion. The ends of the sample are clamped in anInstron Tensile Tester and pulled apart at a crosshead speed of 50.8 cmper minute. The test measures peak stress (in pounds per square inch andconverted to kiloPascals (kPas)), the amount of elongation or peakstrain (in % of the original length), and peak energy (in foot poundsand converted to joules (J).

Static shear Strength

A 2.54 cm by 2.54 cm strip of pressure-sensitive adhesive foam tape islaminated to a 0.51 mm thick anodized aluminum panel measuring about2.54 cm by 5.08 cm. A second panel of the same size is placed over thetape so that there is a 2.54 cm overlap, and the ends of the panelsextend oppositely from each other. The sample is then rolled down with a6.8 kg metal roller so that the total contact area of the sample to thepanel was 2.54 cm by 2.54 cm. The prepared panel is conditioned at roomtemperature, i.e., about 22° C. for at least 1 hour. The panel is thenhung in a 70° C. oven and positioned 2 degrees from the vertical toprevent a peel mode failure. A 750 gram weight is hung on the free endof the sample. The time required for the weighted sample to fall off ofthe panel is recorded in minutes. If no failure has occurred within10,000 minutes, the test is discontinued and results are recorded as10,000+minutes.

Hot Melt Composition 1

A pressure-sensitive adhesive composition was prepared by mixing 90parts of IOA (isooctyl acrylate), 10 parts of AA (acrylic acid), 0.15part 2,2 dimethoxy-2-phenylacetophenone (Irgacure™651 available fromCiba Geigy) and 0.03 parts of IOTG (isooctyl thioglycolate). Thecomposition was placed into packages measuring approximately 10 cm by 5cm by 0.5 cm thick packages as described in U.S. Pat. No. 5,804,610,filed Aug. 28, 1997, issued Sep. 8, 1998 and incorporated herein byreference. The packaging film was a 0.0635 thick ethylene vinylacetatecopolymer (VA-24 Film available from CT Film of Dallas, Tex.) Thepackages were immersed in a water bath and at the same time exposed toultraviolet radiation at an intensity of 3.5 milliwatts per squarecentimeter and a total energy of 1627 millijoules per square centimeteras measured in NIST units to form a packagedpressure-sensitive-adhesive. The resulting adhesive had an IV (intrinsicviscosity of about 1.1 deciliters/gram, Mw of 5.6×10⁵ g/mol and Mn of1.4×10⁵ g/mol.

Hot Melt Composition 2

A packaged adhesive was prepared following the procedure for Hot MeltComposition 1 except that 97 parts of IOA and 3 parts of AA were used.

Hot Melt Composition 3

A packaged adhesive was prepared following the procedure for Hot meltComposition 1 except that 80 parts IOA and 20 parts AA were used.

Hot Melt Composition 4

A hot melt pressure-sensitive adhesive composition having 96 parts IOAand 4 parts methacrylic acid was prepared following the proceduredescribed in U.S. Pat. No. 4,833,179 (Young et al.) incorporated in itsentirety herein by reference.

Hot Melt Composition 5

A packaged adhesive was prepared following the procedure for Hot MeltComposition 1 except that 46.25 parts of isooctyl acrylate, 46.25 partsof n-butyl acrylate (nBA), and 7.5 parts of acrylic acid were used. Thepackaged adhesives was then compounded in a twin screw extruder with 17%Escorez™180 tackifier (available from Exxon Chemical Corp.) to form HotMelt Composition 5.

Hot Melt Composition 6

A hot melt adhesive composition was prepared following the procedure forHot Melt Composition 5 except that the packaged adhesive composition was45 parts IOA, 45 parts nBA, and 10 parts AA were used.

Hot Melt Composition 7

A packaged hot melt composition was prepared following the procedure forHot Melt Composition 1 except that the composition in the packages alsoincluded 0.25 parts of acryloxybenzophenone per one hundred parts ofacrylate.

Hot Melt Composition 9

A hot melt composition having 90 parts IOA and 10 parts AA was preparedfollowing the procedure for Example 1 of U.S. Pat. No. 5,637,646(Ellis), incorporated in its entirety herein by reference.

Hot Melt Composition 9

A hot melt composition having 95 parts IOA and 5 parts AA was preparedfollowing the procedure for Hot Melt Composition 1.

Hot Melt Composition 10

A hot melt composition having 90 parts 2-ethylhexyl acrylate and 10parts AA was prepared following the procedure for Hot Melt Composition1.

Extrusion Process

The packaged hot melt composition was fed to a 51 mm single screwextruder (Bonnot) and compounded. The temperatures in the extruder andthe flexible hose at the exit end of the extruder were all set at 93.3°C. and the flow rate from was controlled with a Zenith gear pump. Thecompounded adhesive was then fed to a 30 mm co-rotating twin screwextruder with three additive ports (Werner Pfleider) operating at ascrew speed of 200 rpm with a flow rate of about 10 pounds/hour (4.5kilograms/hour). The temperature for all of the zones in the twin screwextruder was set at the specific temperatures indicated in the specificexamples. Expandable polymeric microspheres were added downstream to thethird feed port about three-fourths of the was down the extruder barrel.The hose and die temperatures were set at the temperatures indicated forthe specific examples. The extrudate was pumped to a 15.24 cm wide dropdie that was shimmed to a thickness of 1.016 mm. The resulting foamsheets had a thickness of about 1 mm. The extruded sheet was cast onto achill roll that was set at 7.2° C., cooled to about 25° C., and thentransferred onto a 0.127 mm thick polyethylene release liner.

Example 1-5

Foam sheets for Examples 1-5 were prepared using Hot Melt Composition 1in the process described above using varying amounts of expandablepolymeric microspheres having a shell composition containingacrylonitrile and methacrylonitrile (F100D available from PierceStevens, Buffalo, N.Y.). The amounts of microspheres in parts by weightper 100 parts of adhesive composition (EMS-pph) are shown in Table 1.The extruder temperatures were set at 93.3° C., and the hose and dietemperatures were set at 193.3° C. After cooling, the extruded foamsheets were transferred to a 0.127 mm thick polyethylene film andcrosslinked using an electron beam processing unit (ESI Electro Curtain)operating at an accelerating voltage of 300 keV and at a speed of 6.1meters per minute. The measured e-beam dose was 4 megaRads (mrads). Allof the foams were tacky. The foam sheets in Examples 1,2,4, and 5 werebonded (e.g., laminated) to a two-layer film adhesive using pressurefrom a nip roll to make a tape. The first layer of the film adhesive wasprepared by dissolving 10 parts polyamide (Macromelt 6240 from Henkel)in a solvent blend of 50 parts isopropanol and 50 parts n-propanol,coating the solution onto a release liner, and drying and oven at 121°C. for about 15 minutes. The second layer of the film adhesive was asolvent based pressure sensitive adhesive having a composition of 65parts IOA, 30 parts methyl acrylate, and 5 parts AA made according tothe method disclosed in Re24906 (Ulrich), incorporated herein byreference. A release liner was then placed over the solvent basedpressure-sensitive adhesive, and the polyamide side of the film adhesivewas pressure laminated to the foam. The tapes were tested for 90° peeladhesive, T-peel adhesion, tensile and elongation, and static shearstrength. Test results and foam densities for all of the examples areshown in Table 1.

The foam of Example 1 had a surface roughness (R_(a)) of 29 micrometers.

Example 6

A foam sheet was prepared following the procedure for Example 3 exceptthat the extruder temperatures were set at 121° C., and the hose and dietemperatures were set at 177° C. After cooling, the foam was crosslinkedwith a dose of 8 mrads.

Examples 7-9

Pressure-sensitive adhesive coated foam tapes were prepared followingthe procedure for Example 1 except that the extruder temperatures wereset at 121° C. and the amounts of microspheres were 6, 8, and 10 pph forExamples 7,8, and 9 respectively.

Examples 10-13

Foam sheets were prepared following the procedure for Example 3 exceptthat the extruder temperatures were set at 82° C., the hose and dietemperatures were set at 104° C., and according to the conditionsspecified below.

For Example 10, 2 pph expandable polymeric microspheres (F50D availablefrom Pierce Stevens) were used and the extruder flow rate was 4.08 kgper hour.

For Example 11, 2 pph expandable polymeric microspheres having a shellcomposition containing acrylonitrile, vinylidene chloride, andmethylmethacrylate (Expancel 461 encapsulated microspheres availablefrom Akzo Nobel) were used.

For Example 12, 2 pph expandable polymeric microspheres having a shellcomposition containing acrylonitrile, methacrylonitrile, and methylmethacrylate (Expancel 091 available from Akzo Nobel) were used, theextruder temperatures were set at 93.9° C., and the hose and dietemperatures were set at 193.3° C. The foam was measured for mean freespacing. The surface roughness (R_(a)) was 14 micrometers, and a portionof the foam is shown in FIG. 1( a) and 1(b).

Example 13 was prepared following the procedure for Example 12 exceptthat it used 2 pph expandable polymeric microspheres having a shellcontaining acrylonitrile, methacrylonitrile, and methyl methacrylate(F80SD microspheres available from Pierce Stevens) and the extrudertemperatures were set at 93.3° C. Additionally, 0.15 parts by weight perone hundred parts of acrylate of2,4-bis(trichloromethyl)-6-4-methoxyphenyl)-s-triazine was mixed withthe expandable polymeric microspheres and added to the 10 extruder. Theresulting foam was crosslinked with a mercury vapor lamp with 500milliJoules/square centimeter of energy (NIST units). The foam had asurface roughness (R_(a)) of 33 micrometers.

Examples 14-15

Pressure-sensitive adhesive foam tapes were prepared following theprocedures for Examples 2 and 3, respectively, except that the extrudertemperatures were set at 121° C., and 10% by weight of a meltedtackifier (Escorez™180 obtained from Exxon Chemical Co.) was added tothe first port in the extruder barrel. The flow rate of the extrudatewas 4.08 kg per hour of compounded acrylate and 0.45 kg per hour oftackifier. The cooled foam was crosslinked with a dose of 8 mrads.

Example 16

A pressure-sensitive adhesive foam tape was prepared following theprocedure for Example 2 except that 0.2 parts per one hundred parts ofacrylate of a chemical blowing agent (of 4,4′oxybis(benzenesulfonylhydrazide) obtained as Celogen OT from UniroyalChemical Co.) was mixed with the microspheres and to added to theextruder.

Example 17

A pressure-sensitive adhesive foam tape was prepared following theprocedure for Example 2 except that the extruder temperatures weremaintained at 110° C. A mixture of 50 parts by weight F80SD expandablepolymeric microspheres and 50 parts of a chemical blowing agent mixed(BIH, a mixture of 85% sodium bicarbonate and 15% citric acid, availablefrom Boehringer-Ingelheim) was added at a rate of 2 pph. The extruderrate flow was 3.54 kg per hour. The resulting foam was crosslinked withas in Example 1 at a dose of 6 mrads.

Example 18

A foam sheet was prepared following the procedure for Example 3 exceptthat 1.6 pph of F80SD expandable polymeric microspheres were added aswell as 0.4 pph glass bubbles (S-32 available from Minnesota Mining &Manufacturing Company). The microspheres and glass bubbles were mixedtogether before adding to the extruder.

The foam had a surface roughness (R_(a)) of 24 micrometers on one majorsurface and 21 micrometers on the other major surface.

Examples 19-20

Foam sheets were prepared following the above extrusion process usingHot Melt Composition 3 and with 2 pph expandable polymeric microspheres(F80SD). The extruder temperatures were set at 110° C., and the hose anddie temperatures were set at 193° C. The extruder feed rate was 3.58kg/hr. Example 20 also included a plasticizer (Santicizer 141 availablefrom Monsanto) and which was fed into the extruder at 0.36/hr. The foamswere crosslinked following the procedure in Example 1. Example 19 wasfurther laminated to the film adhesive of Example 1.

Example 21

A foam sheet was prepared following the procedure for Example 20 exceptthat Hot Melt Composition 4 was fed directly into the twin screwextruder, and 4 pph F80SD expandable polymeric microspheres were used.

Examples 22-27

Pressure-sensitive adhesive foam sheets having the film adhesive ofExample 2 were prepared following the procedure for Example 2 exceptthat F80 expandable polymeric microspheres were used instead of F100Dand the extruder temperatures were set at 104° C. Additives were alsofed to the first extruder port in the type and amount for each exampleas follows:

Example 22—10% by weight of the extrudate of polyethylene (Engage™8200available from Dow Chemical Co.) was added to the extruder at a rate of0.45 kg/hr in the first port.

Example 23—20% by weight of the extrudate of styrene-isoprene-styreneblock copolymer (Kraton™D1107available from Shell Chemical Co.) wasadded to the extruder at a rate of 0.9 kg/hr. The foam had a surfaceroughness (R_(a)) of 25 micrometers on one major surface and 19micrometers on the other major surface.

Example 24—Same as Example 23 except that no other adhesive waslaminated to the foam.

Example 25—25% by weight of the extrudate of polyester (Dynapol™1402(available from Huls America)was added to the extruder at a rate of 1.13kg/hr.

Example 26—Same as Example 25 except that no other adhesive waslaminated to the foam.

Example 27

A pressure-sensitive adhesive foam sheet was prepared using Hot MeltComposition 7 and 2 pph expandable polymeric microspheres (F80SD). Theextruder temperatures were set at 104° C. and the hose and dietemperatures were set at 193° C. The resulting foam was cooled andcrosslinked with an electron beam dose of 4 mrads at an aceleratingvoltage of 300 kilo-electron volts (Kev).

Example 29

A single layer foam sheet was prepared following the procedure forExample 3 except a 25.4 cm wide vane coextrusion die was used instead ofa drop die, the extruder temperature was set at 104° C., and F80SDexpandable polymeric microspheres were used. There was no flow ofmaterial through the outer vanes. The cooled foam was crosslinked withan electron beam dose of 6 mrads at an acelerating voltage of 300 Kev.

Example 29

A foam sheet prepared following the procedure for Example 28 except thatHot Melt Composition 2 was used.

Example 30

A foam sheet for was prepared following the procedure for Example 29except that F100D expandable polymeric microspheres were used.

Example 31-33

Foam sheets were prepared following the procedure for Example 28 exceptthat the outer vanes were open and a layer of Hot Melt Composition 5 wascoextruded on each major surface of the foam sheet. The thickness of thelayer of Composition 3 was 50 micrometers, 100 micrometers and 150micrometers (i.e., 2 mils, 4 mils, and 6 mils) for Examples 31, 32, and33 respectively. The extruder and hose temperatures for the additionallayers were set at 177° C. The foam sheet of Example 31 had a surfaceroughness of (R_(a)) 24 micrometers.

Example 34

A foam sheet was prepared following the procedure for Example 31 exceptthat the extruder temperatures were set at 93.3° C. and the hose and dietemperatures were set at 171° C. and a tackifier was added. The extruderfeed rate was 4.08 kg/hr for Composition 1 and 0.45 kg/hr for atackifier (Escorez™180). Hot Melt Composition 5 was coextruded to athickness of 100 micrometers on each major surface of the foam. Thecoextruded composite was crosslinked with an electron beam at anaccelerating voltage of 275 Kev and a dose of 8 mrads.

Example 35

A foam sheet was prepared following the procedure for Example 34 exceptthat instead of the tackifier, low density polyethylene (Dowlex™2517available from Dow Chemical Co.)) was added to the extruder at feed rateof 1.36 kg/hr and Composition 1 was fed in at a rate of 3.18 kg/hr. Hotmelt Composition 6 was coextruded to a thickness of 50 micrometers oneach major surface of the foam. The resulting coextruded composite wascooled and crosslinked with an electron beam accelerating voltage of 250Kev and a dose of 6 mrads.

Example 36-37

Pressure-sensitive adhesive foam sheets were prepared following theprocedure for Example 31 except that the microspheres used were a 50/50blend of F80SD and F100D microspheres and the extruder temperatures wereset at 93° C., and the hose and die temperatures were set at 171° C.Example 36 was crosslinked with an e-beam accelerating voltage of 250Kev and a dose of 6 mrads. The outer vanes of the die were opened forExample 37 and the foam was coextruded with 0.15 mm thick layer of lowdensity polyethylene (Dowlex™2517) on one major surface of the foam.After cooling, the polyethylene layer could be removed from theadhesive. This example illustrates the pressure-sensitive adhesive foamwith a liner. Furthermore, the two layer composite can be crosslinkedwith an electron beam to bond the foam permanently to the polyethylene.

Example 38

A pressure-sensitive adhesive foam sheet was prepared following theprocedure for Example 28 except that Hot Melt Composition 8 was feddirectly to the twin screw extruder.

Example 39

A pressure-sensitive adhesive foam sheet was prepared following theprocedure for Example 19 except that Hot Melt Composition 9 was used andthe extruder feed rate was 4.5 kg/hr.

Example 40-42

Foam sheets were prepared by extruding Composition 1 with ethylene vinylacetate copolymer (EVA). The EVA used for Examples 40, 41, and 42 wereElvax™250 (melt index of 25, vinyl acetate content of 28%), Elvax™260(melt index of 6.0, vinyl acetate content of 28%), and Elvax™660 (meltindex of 2.5, vinyl acetate content of 12%) respectively. All of theEVAs were obtained from DuPont Co. Composition 1 was fed to the extruderat a rate of 2.7 kg/hr and the EVA was fed at a rate of 1.8 kg/hr. Aloading of 3 pph F100D expandable polymeric microspheres was used. Theextruder temperatures were set at 104° C. and the hose and dietemperatures were set at 193° C. Additionally, Examples 40 and 41 werecoextruded with a 0.064 mm thick layer of Hot Melt Composition 1 on bothmajor surfaces of the foam. All of the coextruded foams were crosslinkedwith an electron beam accelerating voltage of 300 Kev and a dose of 6mrad. The surface roughness (R_(a)) of Example 40 was 27 micrometers.

Example 43

A non-tacky foam sheet was prepared following the procedure for Example40 except that only EVA (Elvax™250) was extruded with 3 pph expandablepolymeric microspheres (F100D). The surface roughness (R_(a)) was 23micrometers on one major surface of the foam and 27 micrometers on theother major surface of the foam.

Example 44

A foam sheet was prepared following the procedure for Example 40 exceptthat instead of EVA, a high density polyethylene (Dowlex™IP-60 availablefrom Dow Chemical Co.). The feed rates of Composition 1 and thepolyethylene were 3.63 kg/hr and 0.91 kg/hr, respectively.

Example 45

A foam sheet was prepared following the procedure for Example 44 exceptthat a low density polyethylene (Dowlex™2517) was used. The feed ratesof Composition 1 and the polyethylene were 3.18 kg/hr and 1.36 kg/hr,respectively.

Example 46

A foam sheet was prepared following the procedure for Example 44 exceptthat Hot Melt Composition 9 was extruded with a polyester (Dynapol™1157available from Huls) and 3 pph expandable polymeric microspheres (F80).The extruder temperature was set at 93° C. and the hose and dietemperatures were set at 171° C. The end plates of the die were set at atemperature of 199° C. to form a uniform thickness across the sheet. Thefeed rates of Composition 9 and the polyester were 3.18 kg/hr and 1.36kg/hr, respectively. The resulting foam was cooled and then crosslinkedwith an electron beam accelerating voltage of 275 Kev and a dose of 6mrads.

Example 47

A nontacky foam sheet was prepared following the procedure for Example46 except that only polyester (Dynapol™1157) was extruded with 4 pphexpandable polymeric microspheres (F80SD). The foam had a surfaceroughness (R_(a)) of 27 micrometers.

Example 49

A 2.54 cm diameter cylindrical foam was prepared following the procedureof Example 44 except that both Hot Melt Composition 1 and the highdensity polyethylene were fed to the extruder at a rate of 2.27 kg/hrwith 2 pph expandable polymeric microspheres (F80SD). The die wasremoved so the foam was extruded from the hose in a cylindrical shape.

Example 49

A 1.27 cm diameter cylindrical foam was prepared following the procedureof Example 23 except that both Hot Melt Composition 1 and the blockcopolymer were fed to the extruder at a rate of 2.27 kg/hr with 2 pphexpandable polymeric microspheres (F80SD). The die was removed and thefoam was extruded from the hose in a cylindrical shape.

Example 50-52

A foam sheet for Example 50 was prepared by feeding astyrene-isoprene-styrene block copolymer (Kraton™D1107) to the twinscrew extruder of Example 1 at a feed rate of 1.8 kg/hr. A tackifier(Escorez™1310 LC, available from Exxon Chemical Co.) was fed into thefirst port at a feed rate of 1.8 kg/hr. and expandable polymericmicrospheres (F80SD) were fed to the third port at a rate of 2 parts perone hundred parts of block copolymer and tackifier. The extrudertemperatures were set at 121° C. and the hose and die temperatures wereset at 193° C. The resulting foam adhesive had a density of 33.7 lbs/ft³(539.2 Kg/m³). This sample possessed stretch activated release (i.e.,stretch releasable) characteristics such as that described in the Brieset al U.S. Pat. No. 5,507,464, which is incorporated herein byreference.

In Example 51, a foam sheet was prepared following the procedure ofExample 51 except that 8 pph of F80SD expandable polymeric microsphereswere used. The resulting foam adhesive had a density of 16.5 lbs/cubicft (264 kg/m³).

In Example 52, a foam sheet was prepared following the procedure ofExample 51 except that the block copolymer wasstyrene-ethylene-butylene-styrene block copolymer (Kraton G1657available from Shell Chemical Co.) and the tackifier was Arkon P-90(available from Arakawa Chemical USA). The resulting foam adhesive had adensity of 36.9 lbs/cubic ft (590.4 kg/m³). This sample also possessedstretch activated release characteristics as described in the aboveincorporated Bries et al US Patent and published PCT Applications.

Example 53

A foam sheet was prepared following the procedure for Example 31 exceptthat the extruder temperatures were set at 93° C., and the hose and dietemperatures were set at 171° C. The foam was coextruded a 0.1 mm layerof adhesive on each major surface of the sheet. The adhesive was atackified styrene-isoprene-styrene block copolymer (HL2646 availablefrom HB Fuller). The resulting foam had a density of 29 lbs/cubic foot(464 kg/m³).

Examples 54-57

Foam sheets were prepared by feeding polyhexene having an intrinsicviscosity of 2.1 to the twin screw extruder at a rate of 4.5 kg/hr andexpandable polymeric microspheres (F100D) at a rate of 2 pph for Example54 and 4 pph for Example 55. Foam sheets for Examples 56 and 57 wereprepared following the procedure for Examples 54 and 55, respectively,except that the polyhexene was fed to the extruder at a rate of 3.31kg/hr and a tackifier (Arkon P-115 available from Arakawa Chemical USA)was fed to the first port at a rate of 1.63 kg/hr, and the expandablepolymeric microspheres were mixed with 0.3 pph2,4-bis(trichloromethyl)-6-4-methoxyphenyl)-s-triazine before adding tothe extruder.

Example 58

Hot Melt Adhesive Composition 1 was processed in a 10.16 mm Bonnotsingle screw extruder. The extruder was operated at room temperature,relying only on mechanically generated heat to soften and mix thecomposition. The mixture was then fed into Zone 1 of a twin screwextruder (40 mm Berstorff (ZE-40) co-rotating twin screw extruder) whereit was mixed with expandable polymeric microspheres (F100). A standardcompounding screw design was used with forward kneading in Zone 2,reverse kneading in Zone 4, Zone 6, and Zone 8 with self-wipingconveying elements in the remaining zones. Screw speed was 125 RPMresulting in operating pressures of 52.7 kiloPascals and total flowrates of 11.3 kg/hr. The temperatures in the extruder were set at 104°C., and the hose and die temperatures were set at 193° C. Thistemperature profile prevented expansion during compounding and minimizethe rupturing of the expandable polymeric microspheres. Flow of theextrudate was controlled using a Normag gear pump. The expandablepolymeric microspheres were metered into Zone 7 of the twin screwextruder using a Gehricke feeder (GMD-60/2) at rates of 0.23 kg/h. A15.24 cm wide drop die shimmed at 1 mm was operated at 193° C. The webwas cast onto a chilled cast roll and laminated to a release liner at aspeed of 1.5 meters per minute. Following coating, the foam sheet waselectron beam crosslinked using an ESI Electro Curtain at dose of 8 mradat accelerating voltage of 300 keV. The resulting foam is shown in FIG.2( a) and 2(b). The foam had a surface roughness (R_(a)) of 37micrometers.

Example 59-61

These examples illustrate foams that are suitable for use in afoam-in-place application. A foam sheet for Example 59 was preparedfollowing the procedure for Example 3 except that it contained 10 pphF80SD expandable polymeric microspheres and the extruder, hose, and dietemperatures were all set at 88° C. to minimize expansion of the foam inthe die. The foam was not crosslinked and had a density of 55 lbs/cubicfoot (880 kg/m³). After subsequent heating to a temperature of 193° C.for five minutes, the density was reduced to 13 pounds/cubic foot (208kg/m³). A foam for Example 60 was prepared following the procedure forExample 59 except that Hot Melt Composition 2 was used and the extruder,hose, and die temperatures were all set at 104° C. After cooling, thefoam had a density of 60 lbs/cubic ft (960 kg/m³). After subsequentheating to a temperature of 193° C. for five minutes, the density wasreduced to 15 lbs/cubic foot (240 kg/m³). A foam sheet for Example 61was prepared following the procedure for Example 59 except thatpolyester (Dynapol™1157) was fed to the extruder at a rate of 9 kg/hr,and the temperatures for the extruder, hose, and die were all set at110° C. The 1.14 mm thick foam sheet was crosslinked with an electronbeam accelerating voltage of 275 Kev and a dose of 6 mrad.

TABLE 1 Tensile & Elongation Foam 90° Peel adhesion - N/dm T- Peak PeakOverlap EMS Density 1 hr 3 days 7 days 5 days peel Stress Energy ShearEx pph Kg/m³ 21° C. 21° C. 70° C. 100/100 N/dm KPas Elong % JoulesMinutes 1 1 745.6 150.5 210 *843.5 269.5 399 758 730 1.36 10,000+ 2 2668.8 150.5 217 *728 301 353.5 896 645 1.50 10,000+ 3 2 668.8 133 224*598.5 353.5 353.5 896 725 1.77 10,000+ 4 3 608 143.5 217 *682.5 280339.5 965 548 1.50 10,000+ 5 4 561.6 136.5 206.5 *612.5 332.5 203 896499 1.28 10,000+ 6 3 672 122.5 213.5 *672 203 262.5 1172 508 1.2410,000+ 7 6 NT 206.5 126 112 112 NT 621 201 0.39 10,000+ 8 8 NT 77 8466.5 77 NT 586 57 0.08 10,000+ 9 10 NT 77 56 56 56 NT 689 49 0.0810,000+ 10 2 782.4 80.5 101.5 *479.5 171.5 217 689 700 0.82 10,000+ 11 2812.8 91 115.5 437.5 217 231 827 699 1.09 10,000+ 12 2 584 115.5 192.5*605.5 273 231 1393 413 1.50 10,000+ 13 2 516.8 157.5 283.5 *420 241.5213.5 634 491 0.82 14 2 651.2 171.5 231 *717.5 311.5 357 827 612 1.4110,000+ 15 2 651.2 171.5 259 *703.5 *388.5 339.5 827 667 1.46 10,000+ 162 572.8 175 234.5 *595 *483 294 552 595 1.01 10,000+ 17 1 608 77 101.5*577.5 164.5 262.5 4020 623 1.31 10,000+ 18 1.6 524.8 119 157.5 *430.5*448 189 1027 513 1.63 10,000+ 19 2 715.2 73.5 101.5 *507.5 308 245 4254489 3.67 10,000+ 20 2 672 52.5 *290.5 *528.5 *525 185.5 1751 652 2.4510,000+ 21 4 436.8 80.5 77 *203 189 42 586 283 1.36 10,000+ 22 2 NT185.5 269.5 *434 273 NT 552 504 0.73 23 2 NT 150.5 213.5 *486.5 280 NT655 583 0.10 10,000+ 24 2 NT 154 210 *640.5 *528.5 NT NT NT NT 10,000+25 2 NT 157.5 220.5 *504 357 NT 620.55 490 0.08 10,000+ 26 2 NT 178.5*469 *448 *430.5 NT NT NT NT 10,000+ 27 2 NT 154 164.5 *588 241.5 NT620.55 618 0.83 10,000+ 28 2 620.8 154 217 *458.5 *479.5 NT NT NT NT10,000+ 29 2 587.2 91 87.5 *434 112 NT NT NT NT 10,000+ 30 2 624 77 87.5*392 112 NT NT NT NT 10,000+ 31 2 624 192.5 252 *451.5 *395.5 NT NT NTNT 10,000+ 32 2 680 196 238 *469 *455 NT NT NT NT 10,000+ 33 2 713.6 189248.5 *500.5 *430.5 NT NT NT NT 10,000+ 34 2 624 210 255.5 *483 *427262.5 400 725 1.08 10,000+ 35 2 528 52.5 52.5 189 52.5 140 1703 193 0.8210,000+ 36 2 432 80.5 101.5 259 147 133 621 370 0.54 10,000+ 37 2 NT NTNT NT NT NT NT NT NT NT 38 2 400 157.5 *269.5 *161 185.5 126 496 2210.27 10,000+ 39 2 534.4 87.5 171.5 *451.5 276.5 262.5 641 56 1.0910,000+ *Indicates foam split; NT-sample not tested or data unavailable

Examples 62-70 and Comparative Example C1

Pressure-sensitive adhesive foams were prepared following the procedurefor Example 3 with varying amounts of expandable polymeric microspheresshown in Table 2. The extruder temperatures were set at 104° C., and thehose and die temperatures were set at 193° Examples 62-66 containedF100D microspheres and Examples 67-70 contained F80SD microspheres.Comparative Example C1 contained no microspheres. None of the examplewere crosslinked. The tensile (peak stress), elongation and overlapshear test data show that the properties of the foam can be controlledby the amount of expandable microspheres, and the addition of themicrospheres increased the strength of the foam above the samecomposition that has no microspheres. The overlap shear test used is thesame at described above except that the sample size was 2.54 cm×1.27 cm,using a 1000 g load at 25° C.

TABLE 2 EMS Density Peak Stress Overlap Shear Example Pph Kg/m³ KpasElong % Minutes 62 2 590.6 634.34 1064 122 63 4 445.9 661.92 518 169 646 361.5 655.025 515 166 65 8 296 682.605 185 129 66 10 268.1 634.34 169113 67 2 535.5 524.02 940 122 68 4 400.8 0 148 69 6 293 579.18 283 11770 8 233.3 730.87 90 83 C1 0 971.7 544.7 1867 82

Example 71

A pressure-sensitive adhesive foam was prepared following the procedurefor Example 28 except that 5 pph F100D expandable polymeric microsphereswere used with Hot Melt Composition 2 and a hydrocarbon tackifier(Foral™85 available from Hercules, Inc. of Wilmington, Del.) was added.The hot melt composition was fed to the extruder at a rate of 2.9 kg/hrand the tackifier was fed to the extruder at a rate of 1.7 kg/hr. Theextruder temperatures were set at 93° C., and the hose and dietemperatures were set at 177° C. The resulting foam was approximately0.38 mm thick, and was subsequently crosslinked with an electron beamdose of 8 mrad at an accelerating voltage of 300 Kev. The adhesive foamwas laminated to a flexible retroreflective sheeting described in U.S.Pat. No. 5,450,235 (Smith et al), incorporated herein in its entirety byreference.

The retroreflective sheeting with the foamed adhesive was applied atroom temperature to a polyethylene barrel (obtained from TraffixDevices, Inc. of San Clemente, Calif.). The barrel was placed in an ovenat about 49° C. for 3 days. The barrel was removed from the oven andkept at room temperature for about 24 hours. Then the barrel was placedin a truck at about −1° C. for a week. The sheeting with the adhesiveevaluated showed no delamination or buckling from the barrel at the endof the test period.

Inclusion Coextrusion

Peel Adhesion

The foam inclusion coextrusion samples were laminated to a 0.127 mmthick piece of anodized aluminum. A strip of the tape measuring 1.27 cmby 11.4 cm was cut from the sheet and applied to a stainless steelsubstrate. The strip was then rolled down using four total passes usinga 6.8 kg metal roller. The samples were aged for 1 day at 22° C., 50%relative humidity. After aging the panel is mounted in an InstronTensile Tester so that the tape is pulled off at a 90 degree angle at aspeed of 12 inches/minute (30.5 cm/min.). Samples were tested in boththe machine direction (i.e., the direction the foam flows out of the dieor MD), with the peel direction being parallel to the filaments, and thecrossweb direction (i.e., the direction perpendicular to the flowdirection or CD), with the peel direction being perpendicular to thefilaments. Results are determined in pounds per 0.5 inch and convertedto Newtons per cm (N/cm).

Tensile and Flongation

This test was performed according to ASTM D412-92 except as specified. Asample of the foam was cut into a “dog bone” shape having a width of2.54 cm in the middle portion. The ends of the sample were clamped in anInstron Tensile Tester and pulled apart at a crosshead speed of 12inches per minute (30.5 cm/min). The test measures peak stress (inpounds per square inch and converted to kiloPascals (kPas)), and theamount of elongation or peak strain (in % of the original length).

Static Shear Strength

A 2.54 cm by 2.54 cm strip of pressure-sensitive adhesive foam tape waslaminated to a 0.51 mm thick stainless steel panel measuring about 2.54cm by 5.08 cm. A second panel of the same size was placed over the tapeso that there was a 2.54 cm overlap, and the ends of the panels extendoppositely from each other. The sample was then rolled down with a 6.8kg metal roller so that the total contact area of the sample to thepanel was 2.54 cm by 2.54 cm. The prepared panel was conditioned at roomtemperature, i.e., about 22° C. for at least 24 hours. The panel wasthen hung in a 25° C. oven and positioned 2 degrees from the vertical toprevent a peel mode failure. A 1000 gram weight was hung on the free endof the sample. The time required for the weighted sample to fall off ofthe panel was recorded in minutes. The static shear samples were testedto failure, and each sample tested exhibited a cohesive failure mode.

Example 72-84

Foam samples containing embedded thermoplastic filaments were preparedby a continuous extrusion which was carried out using a speciallydesigned co-extrusion die as disclosed in a U.S. Pat. No. 6,447,875,which is incorporated herein by reference in its entirety. A schematicdiagram of these samples are shown in FIG. 4. The continuous foam matrixconsisted of Hot Melt Composition 1 with IOTG concentration of 0.1 wt %and 2 pph F100D expandable microspheres. The adhesive was added to zone1 of a 34 mm Leistritz™ fully intermeshing, co-rotating twin screwextruder available from American Leistritz Extruder Corp., Somerville,N.J., fitted with a gear pump. The microspheres were added using aGericke feeder (GMD-60) into zone 9 of the twin screw extruder. Thetemperature profile of the twin screw extruder was: zone 1=93° C. (200°F.) and zones 2-12=104° C. (220° F.). The screw configuration of thisextruder had two kneading sections prior to microsphere addition and onekneading section after microsphere addition, while the remainder of thescrew was conveying elements. The twin screw extruder had a screw speedof 100 rpm, a gear pump speed of 7 rpm, and a head pressure of 9.1 MPa(1320 psi) which provided flow rates of 13.6 kg/h (30 lb/hr). Thefilament material was a polyethylene-polyoctene copolymer (Engage™ 8200)that was fed to the coectrusion die using a 32 mm (1.25-inch) Killion™single screw extruder (Model KTS-125 available from Davis-StandardKillion Systems, Cedar Grove, N.J.) with a length to diameter ratio of24:1 and three barrel zones that were operated with a temperatureprofile of zone 1—193° C. (380° F.), zone 2—210° C. (410° F.) and zones3 and 4 −232° C. (450° F.). The screw had a Saxton mixing element with acompression ratio of 3:1. The 32 mm extruder was run at 10 rpm with ahead pressure of 5.1 MPa (740 psi) which provided flowrates of 0.9 Kg/hr(2 lb/h). The filaments were co-extruded so as to be embedded into thefoam using a 45 cm (18 in) wide Cloeren™ two-layer multi-manifold die(available as Model 96-1502 from Cloeren Co., Orange, Tex.) that hadbeen modified. The vane had been hollowed out as shown in the previouslyincorporated case U.S. Pat. No. 6,447,875, and the leading edge or tiphad been cut off to make a vane manifold. The vane tip had circularorifices each having a diameter of 508 microns (20 mils) and separatedby a space of 4.1 mm (0.160 in) and extended from the vane tip 2.5 mm(0.100 in) into the matrix flow. The die was operated at 193° C. (380°F.). The foam was cast onto a paper liner at a take-away speed of 1.2m/min (4 fpm) resulting in an overall thickness of 625 microns (25mils). The samples were subsequently electron beam cured using ESIElectrocure e-beam at an accelerating voltage of 300 keV and dosage of 6megarads.

Example 72 was prepared using the aforementioned conditions with a foammatrix consisting of Hot Melt Composition 1 (IOTG=0.1%) and 2 pph ofF100D. No filaments were present. This was accomplished by not operatingthe KTS-125 satellite extruder.

Example 73 was prepared by following the procedure for Example 1 exceptthat the concentration of F100D was 4 pph.

Example 74 was prepared by the aforementioned conditions with a foammatrix of Hot Melt Composition 1 (IOTG=0.1%) with 2 pph F100D. Thefilaments consisted of 10 w % DOW™ Engage 8200 polyolefin elastomer.

Example 75 was prepared by the aforementioned conditions with a foammatrix of Hot Melt Composition 1 (IOTG=0.1%) with 2 pph F100D. Thefilaments, consisted of 20 w % DOW™ Engage 8200 polyolefin elastomer.

Example 76 was prepared by the aforementioned conditions with a foammatrix of Hot Melt Composition 1 (IOTG=0.1%) with 2 pph F100D. Thefilaments consisted of 30 w % DOW™ Engage 8200 polyolefin elastomer.

Example 77 was prepared by the aforementioned conditions with a foammatrix of Hot Melt Composition 1 (IOTG=0.1%) with 4 pph F100D. Thefilaments consisted of 10 w % DOW™ Engage 8200 polyolefin elastomer.

Example 78 was prepared by the aforementioned conditions with a foammatrix of Hot Melt Composition 1 (IOTG=0.1%) with 4 pph F100D. Thefilaments consisted of 20 w % DOW™ Engage 8200 polyolefin elastomer.

Example 79 was prepared by the aforementioned conditions with a foammatrix of Hot Melt Composition 1 (IOTG=0.1%) with 2 pph F100D. Thefilaments consisted of 10 w % Shell Kraton D 1107 thermoplasticelastomer.

Example 80 was prepared by the aforementioned conditions with a foammatrix of Hot Melt Composition 1 (IOTG=0.1%) with 2 pph F100D. Thefilaments consisted of 20 w % Shell Kraton D 1107 thermoplasticelastomer.

Example 81 was prepared by the aforementioned conditions with a foammatrix of Hot Melt Composition 1 (IOTG=0.1%) with 2 pph F100D. Thefilaments consisted of 30 w % Shell Kraton D 1107 thermoplasticelastomer.

Example 82 was prepared by the aforementioned conditions with a foammatrix of Hot Melt Composition 1 (IOTG=0.1%) with 4 pph F100D. Thefilaments consisted of 10 w % Exxon Escorene polypropylene 3445.

Example 83 was prepared by the aforementioned conditions with a foammatrix of Hot Melt Composition 1 (IOTG=0.1%) with 4 pph F100D. Thefilaments consisted of 20 w % Exxon Escorene polypropylene 3445.

Example 84 was prepared by the aforementioned conditions with a foammatrix of Hot Melt Composition 1 (IOTG=0.1%) with 4 pph F100D. Thefilaments consisted of 30 w % Exxon Escorene polypropylene 3445.

TABLE 3 Max Max Stress Elong'n Exam- MD Peel CD Peel MD Static @ @ pleDensity Adhesion, Adhesion, Shear Break Break, # g/cm³ N/cm N/cm(minutes) KPas) (%) 72 0.7348 16.5 13.7 88 650 720.0 73 0.6496 13.9 15.3166 641 546.7 0 0 0 74 0.777 14.5 20.0 98 1055 441.3 75 0.804 9.8 11.095 2050 986.7 76 0.8007 8.9 10.4 138 3233 941.7 77 0.6788 16.9 13.5 164784 720.0 78 0.709 12.2 18.4 233 2245 989.7 0 0 0 79 0.7624 10.6 13.6124 809 823.3 80 0.7948 15.1 15.5 1050 880.0 81 0.7848 12.8 14.0 2731108 873.3 0 0 0 82 0.6449 12.9 11.7 171 1342 4.6 83 0.6785 9.2 19.4 1203918 7.2 84 0.698 8.8 17.2 193 6260 6.8Discussion of Table 3 and FIGS. 8-10

Table 3 displays a summary of the density, peel adhesion, static shear,and tensile/elongation results for Examples 72-84. Only uncrosslinkedinclusion coextrusion sample were evaluated for static shear strength.Only crosslinked samples were evaluated for density, peel adhesion andtensile/elongation.

FIG. 8 shows the peel force as applied in a direction (MD) parallel tothe filament direction as a function of displacement for Examples 73, 77and 78. This Figure demonstrates that as the filament material increasesfrom 0 to 20 wt % the peel adhesion remains essentially constant. FIG. 9displays the peel force as applied in a direction (CD) perpendicular tothe filament direction as a function of displacement for Examples 73, 77and 78. Example 73 shows no structure, while Example 77 and 78 showdramatically different behavior that is characterized by acharacteristic frequency and amplitude. The frequency between maxima inExamples 77 and 78 is exactly the distance between filaments, note thatthis period does not change with concentration. However, the amplitudebetween minima and maxima does change dramatically as the concentrationof filament increases from 10 to 20%. Furthermore, the adhesion valuesin the CD direction is higher than in the MD. Thus by manipulation ofthe filament concentration and distance between the filaments one candesign peel behavior with various qualities in both the directionparallel and perpendicular to the filament direction.

FIGS. 10 shows the peel force as applied in a direction (MD) parallel tothe filament direction as a function of displacement for Examples 72,79, 80 and 81. This Figure demonstrates that as the filament materialincreases from 0 to 30 wt % the peel adhesion is reduced slightly. FIG.11 displays the peel force as applied in a direction (CD) perpendicularto the filament direction as a function of displacement for Examples 72,79, 80 and 81. Example 72 shows no structure, while Example 79, 80 and81 show dramatically different behavior that is characterized by acharacteristic frequency and amplitude. The frequency between maxima inExamples 79, 80 and 81 is exactly the distance between filaments, notethat this period does not change with concentration. However, incontrast to FIG. 9 the amplitude between maxima and minima of the forcedoes not change as the filament concentration increases. Therefore, thefilament type also plays a role in determining the characteristics ofthe peel force/displacement relationship. Not to be bound by theory, webelieve that as the filament material characteristics become moredissimilar from the foam matrix the amplitude between maxima and minimaincreases.

Other unique properties not obtainable by a single component foam systembut obtainable by the inclusion co-extrusion of embedded discretestructures may include, for example, hand tearable lengthwise along andbetween filaments, stretch releasable, enhanced tensile properties,tailored adhesion (see FIGS. 9 and 11 and the corresponding discussion).

Inclusion coextrusion of thermplastic filaments in foam materials candramatically increase the tensile force and elongation characteristicsof the materials. These properties can be manipulated by choosing theoptimum filament material & filament concentration to produce tensileproperties that vary from high stress/low elongation to low stress/highelongation. The adhesion behavior in the direction both parallel andperpendicular to the filament direction can be manipulated by changingthe filament material, filament spacing, and filament concentration.

Oriented Foam Examples 85-92

Single-layer (B) and three-layer (ABA) foam samples were prepared as inExample 1, above, except as noted below. The A layer is an unfoamedpressure sensitive adhesive skin layer formed using the Hot MeltComposition 10. The B layer is a foamed layer formed using the Hot MeltComposition 10, various thermoplastic polymer blend components, andvarious expandable microspheres available from Pierce Stevens, Buffalo,N.Y. The A layer was approximately 2.5 mils thick, and the B layer wasapproximately 40 mils thick. The extruder temperatures were set at 93.3°C., and the hose and die temperatures were set at 176.7° C. Thethermoplastic blend components were added in various concentrations intozone 1, hot melt composition 10 was added in zone 3, and the expandablemicrospheres were was added into zone 9. The pressure sensitive adhesivematerial in the A layers was fed using a 2″ Bonnot single screw extruder(SSE).

Both the A and B layers were pumped from the extruders to a multilayerfeedblock using 0.5 inch (1.27 cm) OD flexible tubing. The A and Blayers were combined into an ABA arrangement using a three layer Cloerenfeedblock (Cloeren Company, Orange, Tex., Model:96-1501) with an ABAselector plug. After the layers were combined in the feedblock thematerials were formed into a planar sheet using a 10″ (25.4 cm) wideUltraflex 40 Die (Extrusion Dies Incorporated, Chippawa Falls, Wis.).The feedblock and die were both operated at temperatures of about 176°C. The ABA construction exited the die and was cast onto atemperature-controlled stainless steel casting drum maintained at 70° C.After cooling, the foam was transferred to a 0.127 mm thick polyethyleneliner and collected on a film winder. Single layer foam constructionswere made by disengaging the Bonnot SSE. The foam samples wereuniaxially oriented at a ratio in the range of from 2.5:1 to 8:1 (i.e.,stretched in the range of from 2.5 to 8 times its length) at roomtemperature.

Example 85 was prepared using the aforementioned conditions with a foammatrix consisting of 80 wt % Hot Melt Composition 1, 20 wt % Dow Engage8200 and 4 pph of F100D. No adhesive skin layers (i.e., A layers) werepresent. The uncrosslinked foam samples were uniaxially oriented orstretched 2.5 times its original length (2.5:1 ratio) at roomtemperature.

Example 86 was prepared by following the procedure for Example 85 exceptthat the composition of the foam matrix was 40 wt % Hot Melt Composition1, 60 wt % Dow Engage 8200, and 4 pph F100D.

Example 87 was prepared using the aforementioned conditions with a foammatrix consisting of 25 wt % Hot Melt Composition 10, 75 wt % ShellKraton D 1107, and 4 pph of F80SD. No adhesive skin layers were present.The uncrosslinked foam samples were uniaxially oriented at a ratio of8:1 at room temperature.

Example 88 was prepared using the aforementioned conditions with a foammatrix consisting of 50 wt % Hot Melt Composition 10, 50 wt % DuPontElvax 260, and 4 pph of F80SD. Adhesive skin layers of Hot MeltComposition 10 were present (ABA). The uncrosslinked foam samples wereuniaxially oriented at a ratio of 2.8:1 at room temperature.

Example 89 was prepared by following the procedure for Example 88 exceptthat the composition of the foam matrix was 50 wt % Hot Melt Composition10, 50 wt % DuPont Elvax 260, and 6 pph of F80SD. These samplespossessed minimal elongation and could not be oriented at roomtemperature.

Example 90 was prepared by following the procedure for Example 88 exceptthat the composition of the foam matrix was 50 wt % Hot Melt Composition10, 50 wt % DuPont Elvax 260, and 9 pph of F80SD. These samplespossessed minimal elongation and could not be oriented at roomtemperature.

Example 91 was prepared using the aforementioned conditions with a foammatrix consisting of 50 wt % Hot Melt Composition 10, 50 wt % ShellKraton D 1107, and 4 pph of F80SD. Adhesive skin layers of Hot MeltComposition 10 were present (ABA). The uncrosslinked foam samples wereuniaxially oriented at a ratio of 6:1 at room temperature.

Example 92 was prepared by following the procedure for Example 91 exceptthat the composition of the foam matrix was 50 wt % Hot Melt Composition10, 50 wt % Shell Kraton D 1107, and 6 pph of F80SD. Adhesive skinlayers of Hot Melt Composition 10 were present (ABA). The samples wereuniaxially oriented at a ratio of 6:1 at room temperature.

TABLE 4 Density, Orientation Post Density, Example # g/cm3 Type/Ratiog/cm3 85 0.5249 LO-2.5:1 0.4518 86 0.523 LO-2.5:1 0.33 87 0.3382 LO-8:10.3489 88 0.3907 LO-2.75:1 0.3605 89 0.3067 Cannot Orient — 90 0.2231Cannot Orient — 91 0.3552 LO-6:1 0.3835 92 0.2933 LO-6:1 0.3136

Thermal Crosslinker Examples 93-96

In Example 93, 100 parts of the Hot melt composition 10 was mixed with 2parts of F80 expandable microspheres and 5 parts of the crosslinkingagent N,N,N′,N tetrakis(2-hydroxyethy) adipamide (available as PrimidXL-552 from EMS Chemie) and extruded through a die, at a temperaturelower than the activation temperature of the crosslinker, to a thicknessof about 1 mm. The resulting foam had a slight amount of gel particlesbut did not inhibit the formation and extrusion of the foam. The foamwas laminated to a silicone coated polyester release liner and cooled. Asecond silicone coated polyester release liner was laminated to theadhesive and the laminate was baked in an oven set at 177° C. for 30minutes. After cooling, the samples were tested for 90° Peel Adhesionaccording to the test describe above except that the samples wereapplied to a metal substrate coated with a DCT5002 automotive paint, andaging was changed as follows. Test results in Newtons/decimeter agingare:

-   -   20 minutes at 22° C.—37.8 N/dm    -   3 days at 22° C.—90.0 N/dm    -   3 days at 100° C./100% humidity—186.3 N/dm    -   3 days at 70° C.—565 N/dm

In Example 94—96, the adhesives are prepared according to the procedureof Example 93 except that the cross-linking agents and compositions usedare as follows:

In Example 94, 50.7 grams of Hot Melt Composition 10, 1.1 grams of F80expandable microspheres, and 5 grams of diclycidyl ether of bisphenol A(available as Epon™828 from Shell Chemical Co.).

In Example 95, 39 grams of Hot Melt Composition 10, 0.8 grams of F80expandable microspheres, 4 drops of a cycloaliphatic epoxy (available asSarCat K126 from Sartomer), 1 drop oftris-2,4,6-(dimethylaminomethyl)phenol (available as K-54 from AnchorCorp).

In Example 96, 39.2 grams of Hot Melt Composition 10, 0.8 grams of F80expandable microspheres 0.1 gram of N,N,N′,Ntetrakis(2-hydroxyethyl)adipamide dissolved in 2 drops of water.

From the above disclosure of the general principles of the presentinvention and the preceding detailed description, those skilled in thisart will readily comprehend the various modifications, re-arrangementsand substitutions to which the present invention is susceptible.Therefore, the scope of the invention should be limited only by thefollowing claims and equivalents thereof.

1. A foam article comprising: an extruded polymer foam formed bypolymerization of one or more monomeric acrylic or methacrylic esters ofnon-tertiary alkyl alcohols, said alkyl alcohols having from 1 to 20carbon atoms; and a homogeneous distribution of a plurality ofthermoplastic expandable polymeric microspheres within the extrudedpolymer foam, said plurality of expandable polymeric microspherescomprising unexpanded expandable polymeric microspheres, at leastpartially expanded expandable polymeric microspheres, or both.
 2. Thefoam article according to claim 1, wherein said extruded polymer foamexhibits a machine (or longitudinal) direction and crossweb (ortransverse) direction standard deviation of density or thickness over anaverage density or thickness (σ/x), respectively, of less than about0.2.
 3. The foam article according to claim 2, wherein σ/x is less thanabout 0.05.
 4. The foam article according to claim 1, wherein saidextruded polymer foam is an adhesive.
 5. The foam article according toclaim 1, wherein said extruded polymer foam comprises at least onepolymer having a weight average molecular weight of at least about10,000 g/mol.
 6. The foam article according to claim 1, wherein saidextruded polymer foam comprises at least one polymer having a shearviscosity, measured at a temperature of 175° C. and a shear rate of 100sec⁻¹, of at least about 100 Pa-s.
 7. The foam article of claim 1,wherein said extruded polymer foam comprises a polymer matrix comprisinga blend of two or more polymers wherein at least one of said polymers insaid blend comprises a pressure sensitive adhesive and at least one ofsaid polymers is an acrylate-insoluble semi-crystalline polymer.
 8. Thefoam article of claim 1, wherein the extruded polymer foam comprises anacrylic polymer foam formed by polymerization of a monomer mixturecomprising: one or more acrylic or methacrylic esters of non-tertiaryalkyl alcohols, wherein said alkyl alcohols have from 1 to 20 carbonatoms; and one or more monomers selected from acrylic acid, acrylamide,methacrylamide, N,N-dimethylacrylamide, itaconic acid, methacrylic acid,acrylonitrile, methacrylonitrile, vinyl acetate, N-vinyl pyrrolidone,isobornyl acrylate, cyano ethyl acrylate, N-vinyl caprolactam, maleicanhydride, hydroxyalkylacrylates, N,N-dimethyl aminoethyl methacrylate,N,N-diethylacrylamide, beta-carboxyethyl acrylate, vinyl esters ofneodecanoic, neononanoic, neopentanoic, 2-ethylhexanoic, or propionicacids, vinylidene chloride, styrene, vinyl toluene, and alkyl vinylethers.
 9. The foam article of claim 1, wherein the extruded polymerfoam comprises an acrylic foam formed by polymerization of a monomermixture comprising: one or more acrylic or methacrylic esters ofnon-tertiary alkyl alcohols, wherein said alkyl alcohols have from 1 to20 carbon atoms; and one or more monomers selected from ethyloxyethoxyethyl acrylate and methoxypolyethylene glycol acrylate.
 10. The foamarticle according to claim 1, wherein the extruded polymer foam iscapable of stretch activated release.
 11. The foam article according toclaim 1, further comprising at least one layer comprising a polymercomposition, said at least one layer bonded to said extruded polymerfoam.
 12. The foam article according to claim 1, wherein said extrudedpolymer foam is at least partially embedded within a separate polymercomposition, said separate polymer composition having a density thatdiffers from said extruded polymer foam.
 13. The foam article accordingto claim 1, wherein said extruded polymer foam has a center and auniform size distribution of said expandable polymeric microspheres frommajor outer surfaces of said extruded polymer foam to the center of saidextruded polymer foam.
 14. The foam article according to claim 1,wherein said plurality of expandable polymeric microspheres comprisesunexpanded expandable polymeric microspheres.
 15. An article comprising:an extruded adhesive layer; and a homogeneous distribution of aplurality of thermoplastic expandable polymeric microspheres throughoutthe extruded adhesive layer, said plurality of thermoplastic expandablepolymeric microspheres comprising unexpanded expandable polymericmicrospheres, at least partially expanded expandable polymericmicrospheres, or both; wherein the extruded adhesive layer comprises apolymer matrix comprising a blend of two or more polymers substantiallyfree of urethane crosslinks and urea crosslinks to eliminate the needfor isocyanates in said polymer matrix, wherein at least one of saidpolymers in said blend comprises a pressure sensitive adhesive polymerformed by polymerization of monomers comprising an acrylate,methacrylate, or combinations thereof; and at least one of said polymersis selected from unsaturated thermoplastic elastomers, acrylatemonomer-insoluble saturated thermoplastic elastomers, acrylate-insolublesemicrystalline polymers, acrylate-insoluble amorphous polymers having asolubility parameter of less than 8 or greater than 11, elastomerscontaining ultraviolet radiation-activatable groups, and pressuresensitive and hot melt adhesives prepared from non-photopolymerizablemonomers.
 16. The article according to claim 15, wherein the extrudedadhesive layer comprises a polymer matrix comprising a pressuresensitive adhesive polymer formed by polymerization of monomerscomprising an acrylate, methacrylate, or combinations thereof.
 17. Thefoam article according to claim 14, wherein said plurality of expandablepolymeric microspheres further comprises at least partially expandedexpandable polymeric microspheres.
 18. The article according to claim15, wherein said plurality of expandable polymeric microspherescomprises unexpanded expandable polymeric microspheres.
 19. The articleaccording to claim 18, wherein said plurality of expandable polymericmicrospheres further comprises at least partially expanded expandablepolymeric microspheres.
 20. The article according to claim 15, furthercomprising at least one layer comprising a polymer composition, said atleast one layer bonded to said extruded adhesive layer.